- It had been raining for several days before the heat began.
- I had been waiting for the bus for 20 minutes before it arrived.
- She had been working as a nurse for two years before she finally decided to become a doctor.
- He had been running continuously for 40 minutes before he felt tired.
- We had been renovating our new flat for about three months before it was ready.
- She had been teaching English at a university for ten years before she started working at our school.
- The doctor had been examining my dog for about two hours before he prescribed some medicine for her.
- We had been friends for 20 years before we fell out over a trifle.
- My grandmother had been busy in the kitchen for three hours before the whole family sat down at the table.
- The heat had lasted in Moscow for two weeks before the long-awaited cool weather came.
Во всех предложениях используется конструкция had been + глагол с окончанием -ing, обозначающая длительное действие, продолжавшееся до другого действия в прошлом.