模块四 语法专练：情态动词
【考点透视】
从近几年的高考试题来看，情态动词是一大热点。每年单项填空题必考一题，通常从三个方面来考查考生对情态动词的运用：一是情态动词本身所表达的意义，如表示禁止、命令、威胁、许诺等意义；can, may, might, need, shall, should等的用法。二是“情态动词+have done”表示推测。三是情态动词后面省略形式的用法区别，如I could (=I could do），I could have (=I could have done)的区别。
（一）can和could的用法
1．表示能力或客观可能性，还可以表示请求和允许。例如：
Can you finish this work tonight?
一Can I go now? 一Yes，you can.
2．could也可表示请求，是委婉的语气，主要用于疑问句，不可用于肯定句，答语应用can，即could不能用于现在时态的简略答语中。例如：
一Could I come to see you tomorrow?
一Yes，you can. (否定答语可用No，I’m afraid not)。
3．表示惊异、怀疑、不相信的态度。(主要用在否定句、疑问句或惊叹句中)
Can this be true?
4．“can (could) + have + 过去分词”的疑问或否定形式表示对过去发生的行为怀疑或不肯定。例如：
He cannot have been to that town.
（二）may和might的用法
1．表示请求、可以与允许的情况，might比may的语气更加委婉。may的否定式为may not，但表示“不可以、禁止”答意思时常用mustn’t代替may not。例如：
一May I take the book out of the reading-room?
一Yes, you may. (No, you mustn’t. / No, you may not. / No, you’d better not.)
2．“may / might + have + v-ed”结构表示对过去行为的推测，含有“想必、也许会”的意思。
She may／might have missed the train.
（三）must和have to的用法
1．must的否定式有两个：mustn’t表示“禁止”；needn’t/ don’t have to是一般疑问句的否定答复。例如：
一Must we hand in our exercise books today?
一No，you needn’t.
2．“must have done”意思是“过去一定做了”；其否定式“can’t/ mustn’t have done”意思是“(过去)不可能做了”；而“needn’t have done”意思是“(过去)没必要做”。
3．must与have to的区别；二者含义很相似，两者往往可以互换使用，但have to有各种形式，随have的变化而定。must与have to有下列几点不同：
（1）must表示的是说话人的主观看法，而have to则往往强调客观需要。
（2）must一般只表示现在，而have to则有更多的时态形式。
（3）询问对方的意愿时应用must。
（4）表示理论上的论断和自然法则的必然性时，应用must。例如：
We must believe that only socialism can save China.
（四）dare和need的用法
1．need表示“需要”或“必须”，作情态动词时，仅用于否定句或疑问句中，在肯定句中一般用must，have to，ought to或should代替。例如：
―Need I finish the work? ―Yes, you must.
注意：needn’t have done表示“本来不必做某事而实际上做了某事”。
2．dare做情态动词时，主要用于疑问句、否定句和条件从句中，一般不用肯定句中。例如：
How dare you say I’m unfair?
3．dare和need常用作实义动词，有时态、人称和数的变化。所不同的是，作实义动词时，在肯定句中，后面通常接带to的不定式，在否定和疑问句中，后面可接带to或不带to的不定式。
（五）shall和should的用法
1．shall常用于第一、第三人称。若用于其他人称时，则表示说话人给对方的“命令、警告、允诺或威胁”。
2．shall用于条约、规章、法令等文件中，表示义务或规定，一般用第三人称，意为“一定”。
3．shall用于if/ when引导的从句中，表示将来的可能性，语气较强，意为“将”。例如：
When I shall see him, I will give him your message.
4．should常表示“惊异、赞叹、不满”等情绪。主语从句中谓语动词要用“should＋动词原形”。
5．should have done意为“应该做而未做”；shouldn’t have done意为“不应该做而做了”。
6．should表示劝告、建议、命令。同义词未ought to。
（六）will和would的用法
1．表示请求、建议等，would比will委婉客气。
2．表示意志、愿望和决心。
3．will be和will have done的结构均表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。
This will be the book you want.
The guests would have arrived by that time.
4．would可表示过去反复发生的动作或某种倾向。would表过去习惯时used to正式，并没有“现已无此习惯”的含义。
（七）ought to的用法
1．ought to表示应该
2．ought to表示推测
3．ought to have done表示过去应做某事而实际未做。（这时ought to和should可以互换）
（八）used to，had better，would rather的用法
1．used to表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变。在疑问句、否定句、否定疑问句或强调句中，可有两种形式。如：
Did you use to go to the same school as your brother?
Used you to go to the same school as your brother?
I usedn’t to go there.
I didn’t use to go there.
She used to be very fat, didn’t she? / use(d)n’t she?
2．had better意为“最好”，后接不带to的不定式。
3．would rather意为“宁愿”，后接不带to的不定式。由于would rather表示选择，因而后可接than。如：
I would rather work on a farm than in a factory.
I would rather watch TV than go to see the film.
I would rather lose a dozen cherry trees than you should tell me one lie.
【题例精析】
【例1】 -Didn’t they come to the party last week?
-Yes. They didn’t want to come with us at first, but then we ____ persuade them.
A. would B. could
C. were able to D. had to
【易错点悟】解答该题的关键在于区别can 与be able to 表示“能力”的用法。
【要点精析】根据上下文语境及讲话人语气，选项动作表示经过努力才完成的。在这种语气的肯定句和疑问句中，常用be able to，在否定句中可用can。
【答案】C
【例2】 You ____ pay too much attention to your reading skill, as it is so important. （2007北京四中交流卷）
A. can’t B. should
C. must D. needn’t
【易错点悟】解答该题的关键是对“can’...”固定短语的理解。
【要点精析】根据句子意义：无论怎么注意你的阅读技巧都不过分。同时句中由于有了结构，只有can’t可以与它构成固定短语，有此含义。其它选项无此意。
【答案】A
【专项检测】
1. I promised to get there before 5 o’clock, but now the rain is pouring down. They ______ for me impatiently.
A. may wait B. ought to wait
C. could wait D. must be waiting
2. He was very brave. Even though she’d hurt her leg, she ________ go back alone.
A. could B. might
C. have to D. was able to
3. You ________ pay too much attention to your reading skill, as it is so important.
A. cannot B. should
C. must D. needn’t
4. I’ve tried several times, but the car just _______.
A. doesn’t start B. wouldn’t start
C. won’t start D. didn’t start
5. Always the old lady ______ sit for hours doing nothing at all.
A. was used to B. would
C. used to D. should
6. There used to be a small school,___________?
A. was there B. wasn’t it
C. usedn’t there D. usedn’t it
7. Our house is on the top of the hill, so in summer the wind _____ be pretty cold.
A. must B. can
C. ought to D. need
8. Haven’t I told you that you __________ have the answer tomorrow morning?
A. will B. shall
C. should D. would
9. I’m surprised that he _______ in the match.
A. should fail B. should have failed
C. would have failed D. may have failed
10. Better go to see my sick colleague right now, ________I?
A. hadn’t B. didn’t
C. don’t D. won’t
11. Sir, you ______ be hunting deer here, for they are preserved by the government.
A. oughtn’t to B. can’t
C. won’t D. needn’t
12. Sorry I’m late. I ______ have turned off the alarm clock and gone back to sleep again.
A. might B. should
C. can D. will
13. - There were already five people in the car, but they managed to take me as well.
- It __________ a comfortable journey.
A. can’t B. shouldn’t be
C. must have been D. couldn’t have been
14. To be on the safe side, we should fill up the tank now, because we ______ run out of gas on the way.
A. can B. would
C. might D. should
15. ____ three people who travel together, there _____ be at least one who ____ be my teacher.
A. Between; can; will B. In; should; could
C. Among; will; may D. Of; must; can
16. -Could you lend me that book you ______ me about when I telephoned you?
-No, I am sorry, I can’t. I gave it to a friend.
A. were telling B. would tell
C. had told D. had been telling
17. -We need a person badly to think up such an idea.
-_______ the new comer have a try?
A. Shall B. May
C. Should D. Need
18. We ________ so tired. We’ve only been to a party.
A. mustn’t have felt B. wouldn’t have felt
C. shouldn’t have felt D. couldn’t have felt
19. Professor Smith, many students want to see you. __________ they wait here or outside?
A. Do B. Shall
C. Will D. Would
20. -How about paying a visit to Mr. Richardson, our former history teacher?
-Good idea. I will e-mail him today so he _____know _________ to expect us.
A. shall; why B. may; when
C. would; why D. will; how
21. -I went to work on foot yesterday, though it _________ cats and dogs.
-You __________ by bus. It was likely to get a cold.
A. is raining; must have gone B. rained; would go
C. was mining; should have gone D. have rained; could have gone
22. You ______ pay too much attention to your reading skill, as it is so important.
A. cannot B. should
C. must D. needn’t
23. I told Sally to fix him up with this job, but perhaps I _________ it out for her.
A. had to write B. must have written
C. should have written D. ought to write
24. My sister met him at the Grand Theatre yesterday afternoon, so he ________ your lecture.
A. couldn’t have attended B. needn’t have attended
C. mustn’t have attended D. shouldn’t have attended
25. Research findings show we spend about two hours dreaming every night, no matter what we ________ during the day.
A. should have done B. would have done
C. may have done D. must have done
26. -Is there any flight to Tokyo today?
- I think there _____, for the weather is too bad.
A. mustn’t be B. mightn’t be
C. needn’t be D. can’t be
27. -I’m told that John had another car accident this morning.
- I believe not. He _____ so careless.
A. shouldn’t have been B. wouldn’t have been
C. couldn’t have been D. mustn’t have been
28. It was playing computer games that cost the boy a lot of time that he __________ doing his lessons.
A. might have spent B. ought to have spent
C. must have spent D. could have spent
29. -I didn’t know you were good friends.
-You _______. I have known her since she moved here. You were studying abroad then.
A. may have B. needn’t have
C. couldn’t have D. must have
30. They must have finished the work by the end of last month, __________?
A. mustn’t they B. haven’t they
C. hadn’t they D. didn’t they
31. -I didn’t see her yesterday.
- Of course, you _____, because he had gone for a trip.
A. can’t B. may not have
C. can’t have D. mustn’t have
32. You ________ phone him if you want to, but you _________. He is sure to phone you.
A. may; mustn’t B. have to; needn’t
C. can; doesn’t need D. can; needn’t
33. - She must have gone back to the valley.
- ______, she _____ have. The entrance to it was nowhere to be found.
A. No; mustn’t B. Yes; might
C. Yes; could D. No; couldn’t
34. He _____ full marks, but he was so careless as to make a spelling mistake.
A. must have gained B. can have gained
C. could have gained D. must gain
35. From what you said, she _____ you about it.
A. mustn’t have told B. can’t have told
C. mustn’t tell D. can’t tell
36. - You ought to have made an apology to Tom yesterday evening.
- Yes, I know I _________.
A. ought to B. have to
C. should have D. must have
37. -Is there a fog in the evening?
-There _______ be. I’ll make a phone call to find it out.
A. must B. would
C. will D. might
38. - _______ he help you with the problem?
-Well, though it is very hard, __________ I’ll do what I can to work it out.
A. Shall; but B. Can; and
C. Must; however D. Will; still
39. -How is that, Joan?
-Yeah, it’s from the boss. She _________ first, whether she likes it.
A. shall go B. ought to have gone
C. should go D. must have gone
40. -Would you like to watch the video, in which you can see foreigners making jiaoji during the Spring Festival?
-Sure, it ______ be very interesting.
A. should B. may
C. can D. will
41. -The door was open.
-It _________ open. I had locked it myself and the key was in my pocket.
A. can not be B. must not be
C. can not have been D. must not have been
42. -Where ________ Margaret have put the empty bottles?
-She ________ them away. They must be somewhere.
A. can; can’t have thrown B. must; needn’t
C. must; must have thrown D. cant; must throw
43. -Mum, I climbed to get the Teddy Bear from the top of the shelf.
-My goodness! You _______ yourself. You ______ do that next time.
A. must have hurt; mustn’t B. should have hurt; can’t
C. may have hurt; mustn’t D. might have hurt; won’t be able to
44. -Shall I go and buy more food and drinks for the party?
-No, we have prepared a fridge of those. That _______ be quite enough.
A. can B. may
C. might D. ought to
45. -Hurry up, Michael! It’s ten to three.
-Goodness me! The class_______. I’ll be late again.
A. must begin B. may begin
C. should have begun D. must have begun
46. When he was there, he ____ go to that coffee shop at the street comer after work every day.
A. would B. should
C. had better D. might
47. -I hear you have written a novel.
-Yes, the book ________ be out in a month or so.
A. can B. dare
C. should D. need
48. -How could I thank you enough?
-Don’t mention it. Any other man _________ that.
A. must do B. could do
C. would have done D. should have done
49. -Why aren’t they here yet?
-They ________ the bus.
A. can have missed B. must be late for
C. may have missed D. might be late for
50. Mike _______ come to see me I don’t want to go out in case he comes.
A. can B. must
C. may D. will
51. The thief ________ in from the kitchen window as the door was closed.
A. may climb B. must have climbed
C. could have climbed D. should have climbed
52. -You didn’t invite Bill?
- __________ him too?
A. Must I invite B. Must I have invited
C. Should I invite D. Should I have invited
53. -Why didn’t you attend the lecture yesterday?
-I didn’t think that we _______ on Sundays.
A. should B. ought to have
C. shouldn’t have D. will have to
54. It’s said that there are plenty of hotels in that town. There ______ be any difficulty for you to find somewhere to stay.
A. wouldn’t B. mustn’t
C. shouldn’t D. needn’t
55. -Would you be here to attend the English party this evening?
-Yes, we _________.
A. shall B. would
C. will D. must
56. On Sundays when I was a child, Father and I _______ get up early and go fishing.
A. could B. would
C. might D. should
57. -You’d better keep quiet in class.
-Sometimes I ________ Yesterday, I was very quiet during my English class.
A. would B. do
C. did D. have
58. I lived with my sister this summer and didn’t have to pay rent. So I ______ save most of my salary.
A. could B. would
C. was able to D. should
59. -Look, John’s fallen asleep.
- Oh, he _______ too late last night.
A. might sit up B. should have sat up
C. could sit up D. must have sat up
60. -I posted the letter a week ago.
-Then they __________ the letter by now. It usually takes four days.
A. can have received B. must receive
C. should receive D. ought to have received
61. He used to teach in that university and I _________ ride past it on my way to work.
A. would B. could
C. should D. might
62. -So you have to leave now.
-Yes, I __________.
-How nice it would be if you could stay a bit longer!
A. have to B. ought to
C. do D. have
63. He _______ Shanghai, for I saw him talking with the headmaster a moment ago.
A. must have gone to B. can’t have gone to
C. mustn’t have been to D. can’t have been to
64. From what I learn about their hotel, the service and the weather, they _____ their holiday very much.
A. wouldn’t have enjoyed B. shouldn’t have enjoyed
C. needn’t have enjoyed D. can’t have enjoyed
65. It is not like Jack to be unfriendly, so he _________ you when you called.
A. can’t have seen B. should not have seen
C. must not have seen D. need not have seen
66. -Many people in England love to give advice on weather reporting.
-Yes, but I think the weather office’s computers _________ be more accurate.
A. can B. must
C. ought to D. might
67. -The farmers lived near the high way.
-________ very noisy.
A. It must have been B. They must be
C. That might be D. There must be
68. She is too slow. She ________ pass the test, but she __________ too little.
A. would; knew B. will; knows
C. would; knows D. will; knew
69. -Mary didn’t turn up last time, did she?
-No. She_________. We had changed our plan.
A. shouldn’t have come B. needn’t have to come
C. didn’t need to come D. needn’t have come
70. -They haven’t finished the work up to now.
-Well, they________.
A. should B. should have
C. would D. must have
71. -Shall I go and buy more fruit for the party?
-No, I have already bought 3 baskets. That _________ be enough.
A. can B. ought to
C. may D. might
72. -Why hasn’t the speaker turned up?
-He _________ the flight. I’ll find it out at once.
A. must have missed B. might have missed
C. would have missed D. could have missed
73. I _______ pay Tom a visit, but I am not sure whether I will have time this Sunday.
A. should B. might
C. would D. could
74. -Who is the girl standing over there?
- Well, if you _____ know, her name is Mabel.
A. may B. can
C. must D. shall
75. It has been announced that candidates (考生)________ remain in their seats until all the papers have been collected.
A. can B. will
C. may D. shall
【答案解析】
1．D。must表示推测。根据句意：他们一定正在等我们。所以用must be waiting。
2．D。由even though可知该题意为：她很勇敢，尽管她腿受了伤，她仍然设法独自回家了。而be able to= manage to，有克服困难设法成功之意。
3．A。cannot / can not / never … too/ enough是一固定搭配，表示“越……越好”、“再……也不过分”。
4．C。考查情态动词will的用法。will表示意志、意愿和决心。
5．B。used to和would都有“过去常常”之意，但used to有今昔对比之意，现在再也不这样了。而would无此用法。
6．C。解此题的关键：一、掌握反意疑问句的基本构成，即“前肯后否，前否后肯”。二、了解used to构成的反意疑问句有两种 （didn’t和usedn’t或usen’t）。三、知道there构成的反意疑问句可由there直接构成，而不用it，所以选择C。
7．B。can作为情态动词，它有一特殊用法，即：表示“有时会”= is sometimes等一般情况。句意为：我们家住山顶，所以有时夏天风会很大。
8．B。shall用于第一、三人称疑问句时表示征求对方意见或指示。二、三人称表示说话人的命令、警告、允诺或威胁。
9．B。should意为“竟然”。should have done意为“竟然做了某事”。句意：我很惊讶，他竟然比赛输了。
10．A。had better是一特殊情态动词，它可以写成better，但无论是had better，还是better，其反意疑问句均由had引导。此外，还遵循“前肯后否”的原则。故选A。
11．A。此题考查情态动词ought to的特殊用法。它有表示“道德法律上的必须”之意。此句意为：“先生，您不能在这捕鹿，它们是国家保护动物”。can’t虽有“不能、不准”之意，但它不表示“法律上的不准，道义上的不能”之意，所以排除B。oughtn’t to相当于shouldn’t，但前者语气更为强烈。won’t表示“不愿、不能”，故排除。needn’t表“不必”，不符合题意。因此排除D。
12．A。can不能用于肯定句中表示推测；will表将来或意愿；should have done意为“本应该……却未……”。句子表达的是一种对过去的猜测，但可能性不大。
13．D。因对话是对过去事情的推测，所以不能选择A和B。从上句意义可知：已坐了5个人的小车里再挤一个人一定不是舒服的旅行。答案为D。
14．C。表示对未来可能出现的一种事实的推测，但不是很肯定。
15．D。谚语：“三人行，必有我师”。
16．A。本句意为“你能把那本我给你打电话时你提到的那本书借给我吗?”，用过去进行时表示对过去情节，场面的描述。
17．A。shall用于第一、第三人称表示请求允许，“让这个新来者试试好吗?”
18．C。“我们本不该觉得这么累，我们只是参加了个聚会嘛”。have been to是已发生的事实，“本不该”也是已经存在的状况。shouldn’t have felt是对已存在的情况的虚拟。shouldn’t“(照常理)本不应该”。
19．B。shall用于第三人称表示征求许可。
20．B。第一句表示要“拜访Mr Richardson”；第二个人因此说我给他发个电子邮件“so (that) he may know”以便于他可以知道“什么时候接我们(期待我们到达)”故选B。
21．C。说话人在主句中使用了过去时态，因此，用来修饰从句的让步状语从句就必定是过去时态，这样，就排除了A、D项。should have done表示的是责备对方应该做某事而没有做，上句已经说明是走路而不是乘车，这样，就把可would go排除了。
22．A。cannot / can not / never … too / enough是一固定搭配，表示“越……越好”、“再……也不过分”。
23．C。should have done意为“本该干某事”。must have done 意为“准是做了”，不合题意。
24．A。couldn’t have done表示对过去情况的推测，“过去不大可能发生某事”。B项表示本不必做某事而实际上却已做了。C项形式错。D项含有责备批评意味，用于肯定句表示在某时间之前应该完成的事而没完成，用于否定句表示本不该做的事却做了。
25．C。根据句意：研究结果表明我们每天都会有2小时在做梦，不管我们白天做了什么。空格处应是表示对白天所做的事情的不肯定的推测。故选C。
25．D。对现在所发生的事情的否定推测。
27．C。对过去发生的事情的否定推测。句意：-有人告诉我John今天上午又出车祸了。-我不相信。他不可能那么粗心的。couldn’t have done意为“不可能做了……”。
28．B。句意：就是玩电脑游戏浪费了这个小男孩很多时间，其实他本应当把时间化在学业上的。ought to have done含有责备批评之意。故答案为B。
29．C。根据此对话的语境，此空应是“你不可能知道，你当时正在国外读书呢”。you couldn’t have是you couldn’t have known we were friends的简略形式。该句式表示对过去有把握的否定推测。A项表示“也许知道”；B项表示 “没必要知道”；D项表示“一定知道”。均不合题意。
30．C。前句是must have +过去分词时，若前句强调对过去情况的推测（一般都有过去时间状语），疑问部分的谓语动词用didn’t + 主语；若前句强调动作的完成，疑问部分的谓语动词用haven’t/ hasn’t +主语。根据题意，by the end of last month（到上月底为止），表示动作的完成。
31．C。can’t have done 表示对过去发生的行为不肯定。
32．D。考查情态动词的用法。can表“可以”，needn’t表“不必”。
33．D。句意：- 她一定回到峡谷了。 -不，不可能的。峡谷口找不到的。must have done的否定形式应是：can’t / couldn’t have done。
34．C。could have done意为“本来可以干某事”。
35．B。can’t have done表示对过去发生的行为的不肯定推测，意为“不可能干过某事”。
36．C。因为题目中由ought to， 其表示过去动作的have在省略回答时不能舍弃。
37．D。might表示把握性小的判断，意为“也许”。从第二句话说话人要打电话查明，说明他不太清楚，所以用might。must表示有把握的推测．would和will表示推测时把握性仅决于must，意为“大概是……”。
38．D。A、B项因为第二空有并列连词，排除，C项第一空意思不对，排除；D项第一空表示“将来”的时间，第二空表示“转折”的含义。
39．A。shall用于第二、三人称。表示意图、意志、允诺、命令、命运或必然结果等，此处表示必然结果“她必须先去”。因为后面的从句说明了这种情况：“不管她是不是喜欢”，说明不由她个人决定。选项C表达不了这种意思。
40．A。should用于情态动词时可以表示“应该会……，一定……吧”。外国人善于做饺子，他们做饺子的情形一定会很有趣。may只是用于不太确定的推测，不足以表达文中的含义can通常情况下用于疑问句和否定句的推测；will表示将来的情况，而外国人做饺子有趣是一般情况下都会发生的事情。
41．C。应该注意上句时态是was，“当时门是开着的”。对过去的事件的否定推测用can not have been。
42．A。must表猜测时，只用于肯定句，而依据They must be somewhere可以判断答案。
43．C。mustn’t表示“禁止”“绝对不可能”，must表示猜测时，语气比may更加肯定。
44．D。ought to可以表示“根据外界的事实或条件做出判断”。can用于推测时常出现在否定句或疑问句中；may和might表示推测的不确定性。
45．D。根据语境，表示有把握的推测，“一定开始上课了”。must + 动词原形是对现在情况推测，must + have done表示对过去或已发生的情况的推测，may表示把握性较小的推测。should表示预期，“应该会，一定会……吧”。
46．A。would在这里的意思是“过去经常做某事”，符合语境，而B、C、D均无法使此句合理通顺。
47．C。should do的意思是“应该会……，-定……吧”，表示“预期”。
48．C。根据语境，是对过去了的事情表示感谢。情态动词 + have done，表示过去。would意为“会，将”。
49．C。根据上下文，他们还没到这里的原因有可能是他们错过了汽车。错过汽车，没按时到一定是一个过去的动作，所以排除B、D项。can表示推测时常用于否定句和疑问句中。故C项是最佳答案。
50．C。may在此表示对将来的事实进行猜测。
51．B。该句表示对过去的事实进行猜测，用C、D项含义均不对。
52．D。问句中使用了过去时态，说明动作发生在“过去”；A、C项表示“现在”或者“将来”，排除。must不能和完成时一起用于疑问句，排除。这里should have done表示应该做某事而没有做，带有批评的口气。
53．A。此句应该用情态动词的省略形式，根据意思应用should。
54．C。wouldn’t表“不会”，一般用在过去时态；mustn’t表“一定不可以，千万不要”；shouldn’t表“应该不会”；needn’t表“没必要”。
55．C。首先排除B、D，B表示一种委婉，此时没必要，D项must语气不对。shall表单纯的将来，而will更好，表示我们将来愿意去。
56．B。“would”表示一种经常性动作，相当于“used to do”，但意思不完全相同。
57．B。do这一助动词既指代了上文的“keep quiet in class”，又表强调，由于此题设置的是通常状态下，故选do，如果用来指过去的动作，则用did。
58．C。would表“会”，should为“应该”，题中could和was able to表“能够”，符合题意。could为天生所能达到的，而was able to是经努力所能达到的，因此符合“省钱”语境。
59．D。译为：-看！约翰睡着了。-他一定是昨天晚上熬夜熬得大晚了。must表示有根据的，较为肯定的推测。
60．D。从by now看应该是完成时态，排除B、C，从It usually takes four days看，应是ought to“应该”，选D。
61．A。would表示过去某一段时间一直重复做的事情。
62．A。have to表示由于客观原因“不得不”，不能分开；ought to等于should，表示“应该”，do在此句中不能用，不能代替have to。
63．B。can’t have done表示对过去情况的一种比较有把握的判断。根据下半句：因为一会儿时间前我看见他正和校长谈话可判断：他不可能去了上海。
64．D。can’t have done表示对过去的行为动作的否定，从上文来看“根据我所了解的情况，他们不可能这个假期很快乐”，A项表示“可能已经，该已”，B项表示“过去该做而未做”，C项表示“本来不需做而实际上做了”。
65．A。can’t have done表示对过去事实的推测，意为“肯定没有……”。should not have done表示不该做而做了；need not have done表示没必要做而做了；只有must have done，无mustn’t have done形式，mustn’t表禁止。根据句意“不像是Jack不友好”，下句是表推测的，“所以肯定是当你喊他时他没看到你”。
66．C。此题考查的是情态动词的用法。can是 “可以、可能、能够”的意思；must则是“必须”；might表推测。联系上下文意，均不可选。而ought to意为“应该”，有更大的事实依据。根据实际情况，the weather office’s computers也确实更准确些，故选C。
67．A。对话中第一句是对过去一件事情的陈述，因此下一句中对过去某种情况的推测应该用must have done句型，故选A。
68．C。前一个空填would，意为“(在过去某个时间)她想要通过考试”，后一空用knows，是在陈述一个事实，意为“但她知道的太少了”。
69．C。shouldn’t have come意为“本不应该来” ，暗含 “她来过了” 的意思，与题意不符；needn’t have to come中need为情态动词，倾向于主观上的“必要”，与题中给出条件“We had changed our plan”不符；didn’t need to come中的need to do表示“(有责任、有义务)做某事”，符合题意。
70．B。should have done意为“本应该做某事(但实际上没做)”。
71．B。四个选项在句中都不错，只根据说话人语气，“已经买了三篮水果”因为不必再买了，说明她认为已经够了，是一种比较肯定的语气，而不是猜测语气。
72．B。在不确定问题答案之前，我们用不肯定的语气“may”或“might”表推测，又因为推测的动作已经发生，B项最正确，符合语境。
73．A。选项A表示“在某种意义上应该干……”；选项B、D均表示“过去的一种可能性”。根据题意，只能选A。
74．C。选项A表示允许，意为“可以”；选项B表示能力，意为“能够”；选项C表示主张，意为“偏偏，偏要”；选项D表示说话者的意图、命令或决心，意为“必须、一定”。故选C。又如：The car must broke down just as we were going on our holiday.
75．D。shall 用于陈述句第二、第三人称时，表示说话人的意图、允诺、警告、命令、决心等，意思是“必须、应该、可以”。句意：据宣布，考生在收卷前必须坐在自己的座位上。
