20. You should be relieving me of the duty at 10 o'clock, but don't hurry if ____; I'll hang on till you arrive.

A. you're not convenient　　　　　　　 B. it is inconvenient

C. it is impossible　　　　　　　　　 D. you're possible

19. The problem is ____ we can improve our reading skills in such a short time.

A. when　　　　　 B. where　　　　　 C. how　　　　　　 D. that

18. I'm afraid I ____ you with a great many questions. Thank you a lot, sir.

A. bother　　　　 B. have to bother　 C. would bother　 D. have bothered

17. -Teenagers are not allowed to go to the net cafe. Is it the best measure to take?

　　 -That's debatable, but ____ they're finally doing something.

A. at least　　　 B. at most　　　　 C. in all　　　　 D. at last

16. We'll have to think twice before we decide to buy a product an ad ____.

A. shows　　　　　 B. suggests　　　 C. makes　　　　 D. praises

15. -Who do you think is the best in our class?

　　　 -Well, I'm afraid there's no ____ answer.

A. easy　　　　　 B. quick 　　　　　C. fixed　　　　 D. certain

14. It is not where someone comes from and what a person looks like ____ is important but ____ he grows up to be.

A. that; that　　 B. what; what　　 C. 不填; it　　 D. that; what

13. -Look! Those guys are sweating out the examination.

　　 -They should work hard ____ it is too late.

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