21. “What’s your opinion on the matter, please?” “Oh, sorry, I _______.”
A. wasn’t to listen B. haven’t listened
C. wasn’t listening D. hadn’t listened
22. “Aha, you’re a chain smoker!” “Only at home. Nobody _______ that but you.”
A. discovered B. had discovered
C. discovers D. is discovering
23. The telephone _______ three times in the last hour, and each time it ________ for my father.
A. had rang; was B. has rung; was
C. rang; has been D. has been ringing; is
24. The thief tried to break away from the policeman who ______ him, but failed.
A. has held B. had held
C. was holding D. would hold
25. When I arrived at the company, the manager ______, so we had only time for a few words.
A. just went away B. had gone away
C. was just going away D. has just gone away
26. “John took a photograph of you just now.” “Oh, really? I ______.”
A. didn’t know B. wasn’t knowing
C. don’t know D. haven’t known
27. “Mike is not coming to the football game this afternoon.” “It’s a shame! He _______!”
A. promises B. promised
C. will promise D. had promised
28. Please call again. Jim _______ a bath just now.
A. has had B. was having
C. is having D. has
29. “Was Andrew there when you arrived?” “Yes, but he ______ home soon afterwards.”
A. had gone B. has gone
C. is going D. went
30. “Where is Mother.” “She is in the kitchen. She _______ the housework all morning.”
A. is doing B. was doing
C. has done D. has been doing
31. The books, ________ the dictionaries, must be put back where they ________.
A. included; were B. to include; are
C. including; were D. including; are
31. 选 C。第一空including不填 included，因为其后带有宾语；第二填 were，是因为它是指“原来放的地方”。
【答案与解析】
1. 选D。根据那个小男孩徘徊的现象，推知他可能是找不到妈妈了。用现在完成时表示结果。
2. 选C。句意为“好在我们（刚才）没有去公园，因为天（现在）已经开始下雨了”。
3. 选D。用现在完成进行时表示持续到现在的一段时间。
4. 选B，用现在完成时表示结果，即你已经错过了机会，其结果是：你只能等。
5. 选C。用现在完成时表示影响。
6. 选B。用现在完成时表示影响或结果，即现在笔不见了，是由于某人已经把它拿走了的结果。
7. 选D。用现在进行时表示现在正在进行的动作。
8. 选A。从下文的语境看，既然现在叫对方重复一遍，说明“没听清对方的最后一点”应发生在过去（即说此话之前）。
9. 选B。用现在完成时表示从过去持续到现在的一段时间。
10. 选B。before 用作副词时不与具体时间连用，泛指“以前”，通常与一般过去时或现在完成时连用。
11. 选C。用现在进行时表示目前的一种状态。
12. 选C。用现在完成时表示影响或结果，即他整个星期都在国外，所以你说你在剧院见过他，你一定是搞错了。
13. 选D。“把书忘在办公室”发生在“去取书”这一过去的动作之前，因此“忘了书”这一动作发生在过去的过去，用过去完成时。句中when表示的是时间的一点，表示在“同学们正忙于……”这一背景下，when所引导的动作发生。因此前一句应用过去进行时。
14. 选D。注意even as 的意思，它表示“正当……的时候”或“恰当……的时候”。
15. 选B。注意下文语境——事实上，我昨天就做完了。从该回答的语气上推测，填空处应填现在完成时态。