Past Perfect Continuous - Practice (Fill In The Blanks) - Mechanical Engineering MCQ

The sentence is the past perfect continuous tense. The rule is :
Sub + had been + V1 + ing + object 
=> Mrs. Sally had been teaching English for thirty years before she retired.

past perfect continous tense

Past Perfect Continuous Tense,
 My father had been trying to fix the broken pipe for an hour before we eventually called a plumber.

The sentence is in the past perfect continuous sentence.
The baby had been crying for fifteen minutes before her mother heard her cry.

The action of preparing the dinner was ongoing for a period of time before the guests arrived. This requires the Past Perfect Continuous tense to show the duration of the activity leading up to another past event.

The action of repairing the road was continuous and occurred over a span of time before the rain began. The Past Perfect Continuous tense is used to emphasize the ongoing nature of the action.

The question focuses on the duration of her studying, which was an ongoing process before the result of passing the exam. The Past Perfect Continuous tense is used to express this time frame leading to the event.