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.

16. She likes everything to be in place整洁；恰当 _before_______ she starts to work.

15. It was not ___until_____ he took off his eyeglasses that I recognized him.

14. I waited ___until_____ he came back.

13. I haven't seen him ____since_____ he moved to the other side of the town.