Diễn đạt một hành động đang xảy ra trước một hành động trong quá khứ (nhấn mạnh tính tiếp diễn). Diễn đạt hành động là nguyên nhân của một điều gì đó trong quá khứ

Read the situations and complete the sentences

1.  We played tennis yesterday. Half an hour after we began playing, it started to rain.

=> We              for half an hour when it              to rain.

Đáp án: had been playing; started

2.   I had arranged to meet Tom in a restaurant. I arrived and waited for him. After 20 minutes I suddenly realized that I was in the wrong restaurant.

=> I              for 20 minutes when I              the wrong restaurant.

Đáp án:  had been waiting; realised

3.  Sarah got a job in a factory. Five years later, the factory dosed down.

=> At the time the factory              down, Sarah              there for five years.

Đáp án:  closed; had been working

4. I went to a concert last week. The orchestra began playing. After about ten minutes, a man in the audience suddenly started shouting.

=> The orchestra              for about ten minutes when a man in the audience              shouting.

Đáp án: had been playing; started

5.  I began walking along the road ten minutes ago and then a car suddenly stopped just behind me.

=> I              along the road for ten minutes when a car suddenly              just behind me.

Đáp án: had been walking; stopped