7.____a___I listen to your advice, I get into trouble.

A. Every time B. When C. While D. Until

6. He was about to go to bed ___d_____ the doorbell rang.

A. while B. as C. before D. when

5. I recognized you ____a____ I saw you at the airport.

A. the moment B. while C. after D. once　

4. ___once一旦____ you begin, I think you must continue.

A. When B. Whenever C. Once　 D. Even if

3. Hardly had he reached the school gate ____b____ the bell rang.

A. while B. when C. as D. as soon as　

2. It seemed only seconds ___b ____ the boy finished washing his face.

A. when B. before C. after D. even if

1. It was quiet __c______ those big trucks started coming through the town.

A. before B. after C. until D. unless　

19. We played outside till sunset, ___after______ it began to rain.

We were playing outside __when___ it started to rain.

___while__ we were playing outside, it started to rain.

如果没有Till sunset ,用when!注意真实情况的合理性！

18. They decided to go back home ____before_____ their money ran out.

17. The thieves ran away ___immediately______ they caught sight of the police.