Test: Practice Test - 7 - Class 10 MCQ

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. The narrator uses the phrase “making trial of everything” (line 7) to present Eppie as

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. According to the narrator, one consequence of Silas adopting Eppie is that he

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. Which choice provides the best evidence for the answer to the previous question?

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. What function does the second paragraph (lines 30-52) serve in the passage as a whole?

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. In describing the relationship between Eppie and Silas, the narrator draws a connection between Eppie’s

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. Which choice provides the best evidence for the answer to the previous question?

Question is based on the following passage.

This passage is adapted from George Eliot, Silas Marner. Originally published in 1861. Silas was a weaver and a
notorious miser, but then the gold he had hoarded was stolen. Shortly after, Silas adopted a young child, Eppie, the
daughter of an impoverished woman who had died suddenly.
Unlike the gold which needed nothing, and must
be worshipped in close-locked solitude—which was
hidden away from the daylight, was deaf to the song
of birds, and started to no human tones—Eppie was a
5 creature of endless claims and ever-growing desires,
seeking and loving sunshine, and living sounds, and
living movements; making trial of everything, with
trust in new joy, and stirring the human kindness in
all eyes that looked on her. The gold had kept his
10 thoughts in an ever-repeated circle, leading to
nothing beyond itself; but Eppie was an object
compacted of changes and hopes that forced his
thoughts onward, and carried them far away from
their old eager pacing towards the same blank
15 limit—carried them away to the new things that
would come with the coming years, when Eppie
would have learned to understand how her father
Silas cared for her; and made him look for images of
that time in the ties and charities that bound together
20 the families of his neighbors. The gold had asked that
he should sit weaving longer and longer, deafened
and blinded more and more to all things except the
monotony of his loom and the repetition of his web;
but Eppie called him away from his weaving, and
25 made him think all its pauses a holiday, reawakening
his senses with her fresh life, even to the old
winter-flies that came crawling forth in the early
spring sunshine, and warming him into joy because
she had joy.
30 And when the sunshine grew strong and lasting,
so that the buttercups were thick in the meadows,
Silas might be seen in the sunny mid-day, or in the
late afternoon when the shadows were lengthening
under the hedgerows, strolling out with uncovered
35 head to carry Eppie beyond the Stone-pits to where
the flowers grew, till they reached some favorite bank
where he could sit down, while Eppie toddled to
pluck the flowers, and make remarks to the winged
things that murmured happily above the bright
40 petals, calling “Dad-dad’s” attention continually by
bringing him the flowers. Then she would turn her
ear to some sudden bird-note, and Silas learned to
please her by making signs of hushed stillness, that
they might listen for the note to come again: so that
45 when it came, she set up her small back and laughed
with gurgling triumph. Sitting on the banks in this
way, Silas began to look for the once familiar herbs
again; and as the leaves, with their unchanged outline
and markings, lay on his palm, there was a sense of
50 crowding remembrances from which he turned away
timidly, taking refuge in Eppie’s little world, that lay
lightly on his enfeebled spirit.
As the child’s mind was growing into knowledge,
his mind was growing into memory: as her life
55 unfolded, his soul, long stupefied in a cold narrow
prison, was unfolding too, and trembling gradually
into full consciousness.
It was an influence which must gather force with
every new year: the tones that stirred Silas’ heart
60 grew articulate, and called for more distinct answers;
shapes and sounds grew clearer for Eppie’s eyes and
ears, and there was more that “Dad-dad” was
imperatively required to notice and account for.
Also, by the time Eppie was three years old, she
65 developed a fine capacity for mischief, and for
devising ingenious ways of being troublesome, which
found much exercise, not only for Silas’ patience, but
for his watchfulness and penetration. Sorely was poor
Silas puzzled on such occasions by the incompatible
70 demands of love.

Q. As used in line 65, “fine” most nearly means

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. The main purpose of the passage is to

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. The author includes the quotation “Air gets pretty unpredictable behind a flapping wing” (lines 17-18) to

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. What can reasonably be inferred about the reason Usherwood used northern bald ibises as the subjects of his study?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. Which choice provides the best evidence for the answer to the previous question?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. What is the most likely reason the author includes the 30 cm measurement in line 30?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. What does the author imply about pelicans, storks, and geese flying in a V formation?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. Which choice provides the best evidence for the answer to the previous question?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. What is a main idea of the seventh paragraph (lines 62-73)?

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. The author uses the phrase “aerodynamic sweet spot” in line 63 most likely to

Question is based on the following passage.

This passage is adapted from Patricia Waldron, “Why Birds Fly in a V Formation.” ©2014 by American Association for
the Advancement of Science.
Anyone watching the autumn sky knows that
migrating birds fly in a V formation, but scientists
have long debated why. A new study of ibises finds
that these big-winged birds carefully position their
5 wingtips and sync their flapping, presumably to catch
the preceding bird’s updraft—and save energy
during flight.
There are two reasons birds might fly in a
V formation: It may make flight easier, or they’re
10 simply following the leader. Squadrons of planes can
save fuel by flying in a V formation, and many
scientists suspect that migrating birds do the same.
Models that treated flapping birds like fixed-wing
airplanes estimate that they save energy by drafting
15 off each other, but currents created by airplanes are
far more stable than the oscillating eddies coming off
of a bird. “Air gets pretty unpredictable behind a
flapping wing,” says James Usherwood, a locomotor
biomechanist at the Royal Veterinary College at the
20 University of London in Hatfield, where the research
took place.
The study, published in Nature, took advantage of
an existing project to reintroduce endangered
northern bald ibises (Geronticus eremita) to Europe.
25 Scientists used a microlight plane to show
hand-raised birds their ancestral migration route
from Austria to Italy. A flock of 14 juveniles carried
data loggers specially built by Usherwood and his lab.
The device’s GPS determined each bird’s flight
30 position to within 30 cm, and an accelerometer
showed the timing of the wing flaps.
Just as aerodynamic estimates would predict, the
birds positioned themselves to fly just behind and to
the side of the bird in front, timing their wing beats
35 to catch the uplifting eddies. When a bird flew
directly behind another, the timing of the flapping
reversed so that it could minimize the effects of the
downdraft coming off the back of the bird’s body.
“We didn’t think this was possible,” Usherwood
40 says, considering that the feat requires careful
flight and incredible awareness of one’s neighbors.
“Perhaps these big V formation birds can be thought
of quite like an airplane with wings that go up and
down.”
45 The findings likely apply to other long-winged
birds, such as pelicans, storks, and geese, Usherwood
says. Smaller birds create more complex wakes that
would make drafting too difficult. The researchers
did not attempt to calculate the bird’s energy savings
50 because the necessary physiological measurements
would be too invasive for an endangered species.
Previous studies estimate that birds can use
20 percent to 30 percent less energy while
flying in a V.
55 “From a behavioral perspective it’s really a
breakthrough,” says David Lentink, a mechanical
engineer at Stanford University in Palo Alto,
California, who was not involved in the work.
“Showing that birds care about syncing their wing
60 beats is definitely an important insight that we didn’t
have before.”
Scientists do not know how the birds find
that aerodynamic sweet spot, but they suspect that
the animals align themselves either by sight or
65 by sensing air currents through their feathers.
Alternatively, they may move around until they find
the location with the least resistance. In future
studies, the researchers will switch to more common
birds, such as pigeons or geese. They plan to
70 investigate how the animals decide who sets the
course and the pace, and whether a mistake made by
the leader can ripple through the rest of the flock to
cause traffic jams.
“It’s a pretty impressive piece of work as it is, but
75 it does suggest that there’s a lot more to learn,”
says Ty Hedrick, a biologist at the University of
North Carolina, Chapel Hill, who studies flight
aerodynamics in birds and insects. However they do
it, he says, “birds are awfully good hang-glider
80 pilots.”

Q. As used in line 72, “ripple” most nearly means