21. I didn't hear the phone.I　　　　 asleep.

A. must be　　　　　　 B. must have been　　

C. should be　　　　 D. should have been

20. Go on　　　　 the other exercise after you have finished this one.

A. to do　　　　 B. doing

C. with　　　　　 D. to be doing

19. This year they have produced　　 grain　　　　 they did last year.

A. as less;as　　　　　 B. as few;as

C. less;than　　　　　 D. fewer;than

18. It is well known that Thomas Edison　　 the electric lamp.

A. invented　　 B. discovered　 C. found　 D. developed

17. I　　　　 ten minutes to decide whether I should reject the offer.

A. gave　 B. was given　 C. was giving　 D. had given

16. Do you know the boy　　　　 under the big tree?

A. lay　　 B. lain　　 C. laying D. lying

15. If my lawyer　　　　 here last Saturday,he　　　　 me from going.

A. had been;would have prevented

B. had been;would prevent

C. were;would prevent

D. were;would have prevented

14. We must get up early tomorrow,　　　　 we'll miss the first bus to the Great Wall.

A. so　　　 B. or　　　 C. but　　 D. however

13. Does John know any other foreign language　　　　 French?

A. except　　　 B. but　　 C. besides　　　 D. beside

12. 　　　　your coat at once.We must hurry.

A. Wear B. Wearing　　 C. Put on 　　　 D. Putting on