23. -Why do you drink so much coffee?

-Well, _________it doesn’t keep me awake in the nights, I see no harm in it.

A. although　　　 B. if　　　　 C. unless　　　　　 D. while

22. Not until all the fish died in the river __________how serious the pollution was.

A. did the villagers realize　　　　　　　 B. the villagers realized

C. the villagers did realize　　　　　　　 D. didn’t the villagers realize

21. Not until I began to work __________how much time I had wasted.

A. didn’t I realize　　　 B. did I realize　　　 C.I didn’t realize　　　　 D. I realized

20. ___________the sun rises, all the stars in the sky disappear.

A. The moment　　　　　 B. Before　　　　　 C. Till　　　　　　 D. For

11-15 BBAAD 16-20 BCBDA

19. It is 50 years _____________the People’s Republic of China was founded.

A. after　　　　　 B. before　　　　　 C. when　　　　　　　 D. since

18. -If he _________, he ___________tat food.

-Luckily he was sent to the hospital immediately.

A. was warned; would not take　　　　　 B. had been warned; would not have taken

C. would be warned; had not taken　　　 D. had driven; wouldn’t have got

17. If it __________for the snow, we ___________the mountain yesterday.

A. were not; could have climbed　　　　　　　 B. were not; could climb

C. had not been; could have climbed　　　　　　　 D. had not been; could climb

16. As she _________the newspaper, Granny _________asleep.

A. read, was falling　　　　　　　　　 B. was reading, fell

C. was reading, was falling　　　　　　 D. read, fell

15. I need one more stamp before my collection ____________.

A. has completed　　　　 B. completes　　　 C. has been completed　　 D. is completed

14. If city noises __________from increasing, people ___________shout to be heard even at the

dinner table in 20 years from now.

A. are not kept; will have to　　　　　　　 B. are not kept; have to

C. do not deep; will have to　　　　　　　 D. do not deep; have to