Although some questions will feature an idiom error, most of the time, idioms present themselves as a smaller scale issue, such as a difference between two answer choices.
Mastering GMAT idioms requires pure rote memorization. Make flash cards for the following list, and master it. It typically takes a dedicated student at least 5-7 flash card pass-throughs to have this extensive list down. It helps to break your flashcard list down into chunks, and to use the accompanying Idiom Drills in the course to confirm mastery.
Your mastery of idioms must satisfy two criteria:
1) Recognition - You must be able to notice these idioms on an actual question. To do that, burn the trigger word into your memory. For example, with “regard as”, burn the word “regard” into your memory so that you can spot it on an actual GMAT question.
2) Memorization - You must memorize the matching word in the idiom pair, so that you can either correct it, or recognize that it’s already correct
GMAT Idiom Groups
AS
perceive as, regarded as, such as [example], think of as, treat as, used as, view as
BY
determined by, fascinated by, hit by
FOR
allows for, craving for, except for, mistake A for B, provide for, rates for, responsible for, sacrifice A for B, sympathy for
FROM
differ from, differs from, different from, discourage from, distinguish A from B, divergent from, independent from, isolated from, prohibit A from B-ing, prohibit from, results from cause, separating from
IN
acquiesce in, consistent in, failed in (attempt), result in, results in effect
ON
based on, centers on, depend on, dependent on, lavished on, talk on, decide on (noun)
OVER
argument over, debate over, dispute over, quarrel over
THAN
better than, less than, more A than, ever more than, contend that, demand that, doubt that, enough A that B, insist that, mandate that, noted that, require that, so A that [noun]
TO
failed to (perform), forbid to, A identical to, intended to, linked to, native to, oblivious to, opposition to, permit A to B, persuade A to B, potential to, prefer A to B, preferable to, prior to, range from A to B, resistance to, seem to, indicate similar to, so A as to [verb], subscribe to, superior to, the right to, try to, whether to, A enough to B, a responsibility to, able to, access to, addicted to, agree to (course of action), agreed to, analogous to, appeal to, as a result of, attend to, attribute to, averse to, aversion to, cater to, compare to (if similar), compared to, conform to, contrast to, correspond to (non-human), decide to (verb), enable A to B, encourage A to B, equal to, expect to
OF
a consequence of, A instead of B, a sequence of, afraid of, an instance of, approve/disapprove of, capable of, Composed of, consists of, danger of, desirous of, in search of, interaction of, native of, out of, relieved of, result of B