21. The workers are repairing the windows __ glasses were broken by strong wind last night.

　　　 　A. their　　　　　　　　　　 B. where　　　　　　　 C. whose　　　　　　　 D. that’s

20. – Hi, John, I have not seen you for a long time. What __ recently?

　　　 　– Carrying on some research on wildlife.

　　　 　A. have you been doing　　　　　　　　　　 B. have you done

　　　 　C. were you doing　　　　　　　　　　　　　　　　 D. did you do

19. At present the room __, please don’t come in.

　　　 　A. is being painted　　　 B. has been painted D. was painted　　　　　　　 D. will be painted

18. We saw that the building __ fire last night and is still __ fire now.

　　　 　A. caught; caught 　　　 B. caught; on　　　　 C. on; on　　　　　　　 D. on; caught

17. __was that the building there stayed up in the heavy earthquake.

　　　 　A. To our surprise　　　　　　　　　　　　　　　　　 B. We are surprised　　　

　　　 　C. What it was surprised　　　　　　　　　　　　　 D. What surprised us

16. –Hey, look where you are going?

　　　 –Oh, I’m terribly sorry. __.

　　　 　A. I’m not noticing　　　 B. I haven’t noticed　　　 C. I wasn’t noticing　　 D. I don’t notice

15. He asked the students to be quiet so that he could hear what the speaker __.

　　　 　A. had said　　　　　 B. said　　　　　　　　　 C. say　　　　　　　　　 D. was saying

14. In big cities during cold winter, many old people __ the dirty air.

　　　 　A. die to　　　　　　　　　　 B. die of　　　　　　　　 C. die for　　　　　　　 D. die from

13. He didn’t agree with me at first but I __ persuade him.

　　　 　A. was able to　　　　　　 B. could　　　　　　　　 C. could be able　　 D. should

12. Corn was not the only food __ was taken to Europe.

　　　 　A. which　　　　　　　　　　 B. who　　　　　　　　　 C. that　　　　　　　　　 D. /