Past Perfect Continuous Tense

The past perfect continuous tense is a verb tense used to describe an ongoing action that started and continued in the past before another action or time in the past. It is formed by using the past perfect of the auxiliary verb "have" (had) with the past participle of the main verb and the present participle (-ing) of the main verb.

The structure is: had been + present participle

Examples:

1. She had been studying for two hours before she took a break.

    In this sentence, the ongoing action of studying (past perfect continuous) happened before the break was taken.

2. They had been waiting at the restaurant for 30 minutes when the reservation was finally ready.

    Here, the continuous action of waiting occurred before the reservation was ready.

3. By the time I arrived, they had been playing tennis for over an hour.

    The ongoing action of playing tennis had started and continued before I arrived.

4. She had been working on her project for weeks before she submitted it.

    In this example, the continuous action of working on the project happened before the submission.

5. We had been living in the city for five years before we decided to move to the countryside.

    The ongoing action of living in the city took place for a specific duration before the decision to move was made.

6. By the time he reached the airport, the flight had been departing for nearly an hour.

    Here, the continuous action of the flight departing occurred before he reached the airport.

In each example, the past perfect continuous tense is used to emphasize the duration and ongoing nature of an action that occurred before another event in the past.