情态动词的考点
湖南高考英语情态动词考点回顾：
〖06湖南〗Some aspects of a pilot’s job___be boring, and pilots often_____work at inconvenient hours.
A.can; have to B.may; can C.have to; may D.ought to; must〖07湖南〗The biggest problem for most plants, which_____just get up and run away when threatened, is that animals like to eat them.
A. shan’t B. can’t C. needn’t D. mustn’t 考点：
〖08湖南〗You don’t have to know the name of the author to find a book.You ______find the book by the title.
A. must B. need C. can D. would考点：〖09湖南〗— It’s the office! So you know eating is not allowed here.
— Oh, sorry.
A. must B. will C. may D. need考点：
〖10湖南〗You______ buy a gift, but you can if you want to.
A. must B. mustn’t C. have to D. don’t have to 考点：
【2011湖南卷,28】No one ________ be compared with Yao Ming in playing basketball.
A. can B. need C. must D. might考点： 总结考点：1：情态动词的基本用法 2. 情态动词表推测
情态动词的试题回顾一： 【考例1】We hope that as many people as possible join us for the picnic tomorrow.
A.need B.must C.should D.can 考点：
【考例2】If it were not for the fact that she sing，I would invite her to the party.
A.couldn’t B.shouldn’t C.can’t D.might not 考点：
【考例3】The World Wide Web is sometimes jokingly called the World Wide Wait because
A.should B.must C.will D.can 考点：
【考例4】You be hungry already— you had lunch only two hours ago。
A.wouldn’t B.can’t C.mustn’t D.needn’t考点：【考例5】Someone is knocking at the door.Who __it be?
A.may B.must C.will D.can 考点：【考例6】How ________ you say that you really understand the whole story if you have covered only part of the article?（03上海卷，29）
A. can B. must C. need D. may 【考例7】I _______ thank you too much for all your help to my son while we were away from home.
A. won’t B. can’t C. can D. will 考点： 归纳：
can（could）
1.表能力，在肯定句中指过去做某事的能力，泛指一般能力用could,只表具备做某事的能力，但并不表明是否干成。如：If I could plan to do anything I wanted to, I’d like to go to Tibet and travel through as much of it as possible. 注意：①be able to 强调经过努力、克服困难等完成某事；则was/were able to表示过去经过努力等成功的做成了某事；
2.表惊讶等感情色彩，仅用于疑问句、否定句和感叹句中。如：
How can you say that you really understand the whole story if you have covered only part of the article?
3.表推测，常不用于肯定句中，若用于肯定句中则表偶尔一时的特征，译作“有时会”；而can’t表不可能。如：
The World Wide Web is sometimes jokingly called the World Wide Wait because it can be very slow. -----Isn’t that Ann’s husband over there?
-----No, it can’t be him. I’m sure he doesn’t wear glasses.
4.表许可，在请求对方许可时，can 在口语中常用；在准许对方做某事时，答语用can,不用could。如：A left-luggage office is a place where bags can be left for a short time, especially at a railway station.
------Could I borrow your dictionary?
-----Yes, of course you can.
（5）能不能。。。，要不要。。。（用于疑问句，表示客气的请求、提议）
Can you give me a lift to the station?
Can’t you lend me 10 dollars？请你借给我10美元吧？
（6）构成下列特殊句式：
①can not/ can never...too...或cannot...enough...“无论怎么。。。也不过份； 越。。。越好 ；非常。。。” One cannot be too carefull. 越认真越好。
②cannot help doing.../ cannot help but do.../ cannot but do...”“禁不住；不由得；不得不”
When a close friend dies, you cannot feel but sad. 当一个密友死的时候 ， 你会禁不住伤心的.
(7) can 还可以用于一般疑问句和否定句表示推测？someone is knocking. Who can it be ? 而在肯定
句中表推测要用must和may
【2012全国卷II】⒘ I’m going to Europe on vacation together with John if I ___ find the money. A. can B. might C. would D. need
1．There’s no light on—
A.can’t B.mustn’t C.needn’t D.shouldn’t ，I’d like to go to Tibet and travel through as much of it as possible.
A.would B.could C.had to D.ought to
3. It is usually warm in my hometown in March，but it A.must B.can C.should D.would
A.shall B.should C.can D.must
5. The importance of saving gas be stressed too much.Automobiles use up some 70 billion gallons of gas a year.
A.shouldn’t B.mustn’t C.cannot D.may not
6. Even if you are an experienced teacher，make some mistakes.
A.can B.must C.should D.will
7.-Look,it ____be Tom.
-No,it _____be him.He has gone to Beijing. A.may,mustn't B.must,may C.must,can't D.can,may not
情态动词的试题回顾二：
【考例1】-Must I turn off the light now?
-No. you ____.
A.needn't B. mustn't C. can't D. won't 考点：
【考例2】Children under 12 years of age in that country be under adult’s supervision when in a public library.
A.must B.may C.can D.need 考点：
【考例3】. Tom，you leave all your clothes on the floor like this!
A.wouldn’t B.mustn’t C.needn’t D.may not 考点：
【考例4】【2012重庆】-___ _you interrupt now? Can’t you see I’m on the phone?
-Sorry Sir, but it’s urgent.
A. Can B. Should C. Must D. Would 【考例5】Naturally，after I have told her what to do，my daughter go and do the opposite!
A.may B.can C.must D.should 考点：
【考例6】. ---What’s that terrible smell ---Oh，I forgot about the chicken!Go and look，it !
A.may be burnt B.ought to be boiling C.can be cooking D.must be burning 考点： 归纳：
must
(1) 必须、得、要（表义务、必要性、命令）Animals must eat to live.(为了活下去，动物必须吃东西。) ---Must I washing the sidhes at once?
---No, you needn’t.. / yes , you must
注： mustn’t 表示“禁止、不准”。Eg: You mustn’t play with the knife; you might hurt yourself.
(2) 必定（表必然性）。 Everyone must die. 每个人都必定会死。
（3）偏偏、偏要、硬要（表固执、不满等）：If you must know, I’m going to help him look for an apartment.
如果你偏要知道，那我告诉你，我要去帮他找一套公寓。
（4）想必、一定、准是（表推测，只用于肯定句）。 He must be ill. He looks so pale.
(5) must 的否定回答用： No, you needn’t/ No, you don’t have to
1. — Could I have a word with you，mum? — Oh dear，A.can B.must C.may D.should
2. John，look at the time. you play the piano at such a late hour?
A.Must B.Can C.May D.Need
3. In crowded places like airports and railway stations， take care of your luggage. A.can B.may C.must D.will
情态动词的试题回顾三：
【考例1】-----Excuse me. Is this the right way to te Summer Palace?
------Sorry, I am not sure. But it ______ be.（04湖北卷，26）
A. might B. will C. must D. can 考点：
【考例3】 Liza ___ well not want to go on the trip --- she hates traveling.（08全国卷II，17）
A. will B. can C. must D. may考点：【考例4】 Although this ____ sound like a simple task, great care is needed.（08四川卷，10）
A. must B. may C. shall D. should 考点：【考例5】- _____ I watch TV this evening?
- Yes,but you ______ finish your homework first.
A.Must;can B. May;must C. Must;may not D. Must,can't考点：
【考例6】-____I sleep here?
-No,you ___.
A.May;needn't B. May;mustn't C. Can;need D. May;may考点：
归纳：
may/ might
(1) 可以。。。（表准许、请求） eg: You may go home now, Susan. 苏珊，你现在可以回家了
表许可：在请求对方许可时，may较正式，might较may委婉；在准许对方做某事时，答语用may,而不用might。如：
-----I hear you’ve got a set of valuable Australian coins. May I have a look?
-----Yes, certainly.
(2) 但愿；祝。。。(表愿望、祝福；此时，句子要用倒装语序) May you succeed.祝你成功。
(3) 为了，为了能够（用于目的状语从句so..that.../ such....that....）
He works hard so that he may get good grade.
(4) 即使，无论（用于让步状语从句中） Whatever he may say, I don’t believe him.
(5) 构成句型 may as well do sth/ might as well do sth (不妨去做某事，还是做某事的好)
(6) May 的否定回答不用may，
---May I use your bike?
---No, you mustn’t/ You’d better not. / please don’t (肯定：Yes, please. / Certainly)
2.表推测，might比may更不肯定；may not，表“可能不”。如：
------Excuse me. Is this the right way to the Summer Palace?
------Sorry, I am not sure. But it might be.
You might just as well tell the manufacture that male customers may not like the design of the furniture. 练习： 1 Although this sound like a simple task，great care is needed
A.must B.may C.shall D.should2. Helen go on the trip with us，but she isn’t quite sure yet.
A.shall B.must C.may D.can
3. Some people who don’t like to talk much are not necessarily shy；A. must B. may C. should D. would
【2012四川】19. I got close enough to hear them speaking Chinese, and I said “Ni Hao ” just as I ____ do in China.
A. must B. might C. can D. should
情态动词考题回顾四：
【考例1】-----What’s the nurse?
-----Khulaifi. _____ I spell that for you?
A. Shall B.Would C. Can D. Might 【考例2】-----Excuse me, but I want to use your computer to type a report.
-----You ______ have my computer if you don’t take care of it.（04湖南卷，28）
A. shan’t B. might not C. needn’t D. shouldn’t
【考例3】-----What does the sign over there read?
------“No person _______ smoke or carry a lighted cigarette, cigar or pipe in this area.”
A. will B. may C. shall D. must 考点：
归纳：
shall
(1) 用于第一、第三人称，表示征求对方意见，请求指示等：Shall we go out for a walk?
注：may 征求对方的许可，而shall是征求对方意见
May I have a look?我能看一下嘛？？Shall I have a look? 要我看一下嘛？？
(2) 用与第二、第三人称，表示说话人的命令、警告、强制、允诺、威胁或决心等：
eg：He shall be sorry one day, I tell you. 我告诉你，他早晚有一天会后悔的（警告）
Don’t worry. You shall get the answer this very afternoon. (允诺)。
Nothing shall stop us from carrying out the plan. (决心)
应。。。/须。。/ 得。。(用于法律、规则等条文中)： The fine shall be given in cash.罚款应以现金
（3）.其否定形式shan’t表禁止或威胁。如：
----Excuse me, but I want to use your computer to type a report.
----You shan’t have my computer if you don’t take care of it.
【2012辽宁】24. One of our rules is that every student ____ wear school uniform while at school.
A. might B. could C. shall D. will
情态动词考例回顾五：
【考例1】------How is your tour around the North Lake? Is it beautiful?
-------It ______ be, but it is now heavily polluted. (07全国卷I,27)
A. will B. would C. should D. must
【考例2】------Turn off the TV, Jack. _______ your homework now?
-------Mum, just ten minutes, please.（07辽宁卷，30）
A. Should you be doing B. Shouldn’t you be doing
C. Couldn’t you be doing D. Will you be doing 考点：
【考例3】 What do you mean, there are only ten tickets? There be twelve
A. should B. would C. will D. shall should
(1) 应该（表义务、责任） ：We should attend the meeting .我们应该参见这次会议。
（2）应该会、想必会、一定会（表预期）：The concert should be great fun. 音乐会一定很有意思。
I should pay Tracy a visit, but I’m not sure whether I will have time this Sunday.
3 .表推测，should not表“也不应该”，为否定推测，而should为肯定推测，表“也按道理应该”。 There shouldn’t be any difficulty about passing the road test since you have practiced a lot in the driving school.
It’s nearly seven o’clock, Jack should be here at any moment.
情态动词考题回顾六：
【考例1】------We have booked a room for today and tomorrow.
-------________ sir.（07全国卷II，7）
A. I’m sure. B. My pleasure C. It’s right. D. I’ll check.
【考例2】------Mr. Gordon asked me to remind you of the meeting this afternoon. Don’t forget it! ------OK. I _______.
A. won’t B. don’t C. will D. do
【考例3】Turn on the television or open a magazine and you ______ advertisements showing happy families. (04湖南卷，25)
A. will often see B. often see C. are often seeing D. have often seen
【考例4】 John promised his doctor he ________ not smoke, and he has smoked ever since.（08北京卷，
A. might B. should C. could D. would.
will
(1) 表意愿，用于各种人称陈述句：If you will read the book, I’ll lend it to you. 如果你愿意读这本书。。。
（2）表请求，用于疑问句：Will you close the door? It is a bit cold.
(3) 表示某种倾向或习惯性动作：The door won’t open.(这门打不开) Fish will die out of water.
(4) 表命令、叮嘱： No one will leave the examination room before 12 o’clock.12点前谁也不得离开考场。
（5）表猜测：That will be the postman at the door. 门口想必是邮差。
would
(1) 常常、经常（表过去的习惯性动作）：We would stay up all night talking our future.
区别：used to ____________________________________________________________
(2) 老是、（表示说话者的厌烦、焦躁）：That’s exactly like Susie. She would come to me just when I was busy.苏西就是那个样子，她老是在我忙碌的时候来找我。
（3）就是（不能）（用于否定句，主语一般是物，表某物一时的、暂时的特性）That door wouldn’t open.
(4) 表示客气的请求、建议；或婉转的表达个人的想法、看法：Would you mind if I open the window?
1.We had to make the corrections by hand as the computer do them for us.（08四川延考区，12）
A. mightn’t B. needn’t C. shouldn’t D. wouldn’t
【2012江苏】28. Days later, my brother called to say he was all right, but ____ say where he was.
A. mustn’t B. shouldn’t C. wouldn’t D. mightn’t
have to (would rather+do)
have to和must的意义相近，只是 must侧重表示说话人的主观看法，而have to 则表示客观需要，如：I must study hard. I had to give it up because of illness.
11. need 和 dare
这两个词都即可用作情态动词， 也可用作实义动词。
① 用作情态动词，主要用于否定句和疑问句； 用作实义动词，主要用于肯定句（当然也可以
用于否定句等）
② 用作实义动词：You needn’t do it yourself.=You don’t need to do it yourself.
I need to tell them the news.
③ need的主语是物时，其后的动词可以是：doing或to be done.“需要”
The table needs painting. = The table needs to be painted.
④ dare 在否定句中，用作实义动词时，其后的to可带，也可以不带。
He did not dare (to) look up. 他不敢抬头看。
⑤ I dare say.... 为固定习语，意思是“我敢说。。。。”
情态动词考点二：表推测
表示对目前或将来情况的推测往往用“情态动词＋动词原形”这种结构。
1．can用于肯定句中有时可以用来表示推测，意为“有时会”；用于疑问句中可以表示推测，意为“可能”，有时表示一种惊讶的语气；用于否定句中也可以表示推测，can’t 意为“不可能”，语气很强烈。
Mr.Bush is on time for everything.How can it be that he was late for the meeting?
布什先生做什么事情都很准时，他怎么可能开会迟到呢？
The story can’t be true. 这个故事不可能是真的。
2．may用于肯定句中可以用来表示推测，意为“可能”；用于否定句中也可以表示推测，may not意为“可能不”，表示一种不太确定的语气。may在疑问句中不能表示推测。
Peter may come with us tonight，but he isn’t sure yet. 彼得今晚可能和我们一起来，但他还没确定。
3．must 表示推测时只能用于肯定句中，意为“一定，必定”，表示十分肯定的语气(在疑问句中或否定句中要用can)。
He must be ill.He looks so pale. 他准是病了，他的脸色苍白。
—It’s the office！So you must know eating is not allowed here. —Oh，sorry.
“这是办公室！所以你一定知道这里不许吃东西。”“噢，对不起。”
4．should 用来表示推测时意为“应该”，即含有“按道理来说应当如此”的意思。
There shouldn’t be any difficulty about passing the road test since you have practiced a lot in the driving school. 因为你在驾校训练了那么多，通过路考应该没什么困难。
-----I think I’ll give Bob a ring.
------You ______ . You haven’t been in touch with him for ages.
A. will B. may C. have to D. should
5．表示对现在正在发生的事情进行推测要用“情态动词＋be＋现在分词”这种结构。这种结构在高考题中出现的次数不太多，但也提醒考生注意。
My mother must be watering the flowers in the garden now.
现在我母亲一定正在花园里浇花。
The students may be climbing the mountain at the moment.
此刻学生们有可能正在爬山。
基础练习：
1. -shall I tell John about it? -No,you ___________.
A.needn't B.wouldn't C.mustn't D.shouldn't
2. Peter _____come with us tonight. But he isn't very sure yet.
A.must B.can C..may D.will
3 -______ I open the door for you?
-No,thanks.I can manage by myself.
A. Will B. May C. Shall D. Should
4 One ought _______ for what one hasn't done.
A.not to be punished B.to not be punished C.be not to punished D.not be punished
5 The fire spread through the hotel very quickly but everyone ______escape.
A.had to B.would C.could D.was able to
6. A computer _____ think for iself; it must be told what to do.
A.can't B.couldn't C.may not S.might not
7. Tell Tom that he ____have the book next week.
A.shall B.will C.can D.would
8 If you really want yourself to be in good health.you must____always_____so much.
A.not;be smoking B.not;have smoked C.to not;be smoking D.not be;smoked 9 Don't be worried.The news ___ be ture.
A.may not B.mustn't C.needn't D.won't
10 "It's possible that Mr.wu is working now."
The sentence means ______.
A. Mr .Wu must be working now B. Mr . Wu can't be working now
C. Mr . Wu should work now D. Mr .Wu may be working now
11 You ___ so early.
A.need come B.doesn't need come C.needs come D.needn't come
12. We ____ them.They can do it by themselves.
A.need help B.don't need help C.don't need to help D.needn't to help
13. You'd better ___ in class.
A.not talk B.not to talk C.don't talk D.not talking
14. You ____ go with us now,or you will be late.
A.shall B.should C.would D.could
15 - Need I go to work now?
-Yes,you ____.
A.need B.can C.may D.must
16 Could you tell me if there ____plenty of rain in your hometown?
A.is B.would be C.are D.was
17. A boy was crossing the street in front of my car,and I _____ stop very quickly.
A.must B.have to C.has to D.had to
.
A.need repairing B.needs to repair C.needs repairing D.need to repair
情态动词考点三、 情态动词+have done的用法：
情态动词+have done一定表述的是过去的事情，且表示对过去发生的事情的推测、判断，或表某种强烈的语气（如惊讶、责备、赞叹等）
⑴ must + have done 表“过去肯定发生了某事”。The room is clean. Someone must have cleaned it. 注：绝对没有下面的形式：mustn’t have done.
⑵ may/might + have done 表示“过去可能发生了某事”，其中might 的语气要婉转些；但是主句中
动词是过去时，一定要用might, 如He said she might have missed the train.
⑶ could + have done,表示“过去本来能够做成某事，但是没有做到”:You could have succeeded. ⑷ can’t/couldn’t have done 表示“绝不可能发生了某事”：
He couldn’t have taken all the medicine at a time.
⑸ should/ought to +have done, 表示“过去本来应该做某事，但实际上未做”
You are late again. You ought to have come one hour earlier.
⑹ shouldn’t+ have done/ 或oughtn’t to have done, 表示“过去不应该做某事而做了某事”
This is my letter. You shouldn’t have opened it.
⑺ needn’t + have done 表示“本没有必要做某事，而做了”
There was plenty of time, so she needn’t have hurried. 有充足的时间，所以她没有必要哪么急的。。
四、must 表示推测时：其反义疑问句的构成如下：
He must be a teacher, ______________?
She must have finished the work, _____________?
She must have finished the work last night, ______________?
She must have finished the work by the end of last month, ___________?
练习题：
1You mother must be at home,_____ she?
A.mustn't B.doesn't C.isn't D.can't ， for her bike is still here.
A.can’t B.wouldn’t C.shouldn’t D.needn’t
3. What a pity!Considering his ability and experience， he better.
A.need have done B.must have done C.can have done D.might have done
4—I can’t find my purse anywhere. —You have lost it while shopping.
A.may B.can C.should D.would
5. It_____ have been Tom that parked the car here, as he is the only one with a car.
A. may B. can C. must D. should答案 C
6.—I’m sorry.I at you the other day.
—Forget it.I was a bit out of control myself.
A.shouldn’t shou B.shouldn’t have shouted C.mustn’t shout D.mustn’t have shouted
7 Thank you for all your hard work last week.I don’t think we
A.can manage B.could have managed C.could manage D.can have managed
8.-----Where is my dictionary? I remember I put it here yesterday.
-----You _______ it in the wrong place.（07江西卷，27）
A. must put B. should have put C. might put D. might have put
9 ---I can’t find my purse anywhere.---You have lost it while shopping.（08重庆卷，30）
A. may B. can C. should D. would
10-----My cat’s really fat.
-------You ______ have given her so much food.（07浙江卷，15）
A. wouldn’t B. couldn’t C. shouldn’t D. mustn’t
1I told your friend how to get to the hotel, but perhaps I _______ have driven her there.
A. could B. must C. might D.should
12 --- I’m sorry. I ___________ at you the other day. --- Forget it. I was a bit out of control myself.
A. shouldn’t shout B. shouldn’t have shouted C. mustn’t shout D. mustn’t have shouted
13. She _____have had a hard life since she looked much older than her age.
A.may B.may not C.mustn't D.must
14 He went home because his mother was ill.We ____have waited for him at the bus station for a long time.
A.needn't B.need C.must D.shall
15. Mr Wang is wet through.He ___caught in the rain.
A.must be B.must have been C.must has been D.must nave
【2012浙江】19. Had they known what was coming next, they _____ second thoughts.
A. may have B. could have C. must have had D. might have had
[基础训练：答案与解析]
1.A。needn't意为“不必”；wouldn't意为“不会”；mustn't意为“不许或禁止”；shouldn't意为“不应
当”。根据题意，回话人强调对方“不必做......”。故选A.
2.C。Must come表示必须来；can come 能够来；may come 可能来；will come 将要来；根据题意，
说话人的语气表示推测，且不很肯定，故选C.must 表示推测，意为“一定或准是”，只用于肯定句中；can表示推测，意为“可能，或许”，一般用于疑问句或否定句中，但could也可用于肯定句，表示对某事把握不大；may表示推测，意为“或许，可能”，一般英语肯定句或否定句。
3.D。根据题意，说话人对已经发生的事情进行否定推测，故选D。表示对过去发生的事情进行推测，
常用can/may/might/must+have+动词分词。
4.B。此题表示对过去事情的肯定推测，应选B。
5.C。根据语境可知，问句是征求对方意见，故C。
6.A。情态动词ought后接带to的不定式，ought to do的否定式是ought not to do，故选A。
7.D。根据题意，可首先排除A和B。Could表示一种能力；was able to表示在困难的情况下，经过一番周折而“能”。
8.C。Should(ought to) have done sth.表示“过去本应该做某事而没有做到”，含有责备,后悔的意思；
must have done sth.表示对过去动作或行为的推测。根据题意应选C.
9.A。题中的can't是指能为。Couldn't是can't的过去式，这里讲的是一个客观事实，要用一般现在时。
10.A。Shall用于第二，三人称陈述句中表示说话人给对方的命令，警告，允诺，威胁等概念。
11.A。must not always be doing sth.表示“不要老是做某事”，含有埋怨，指责，反感等感情色彩。
12.D。根据题意，本体是谈论过去的事情，A,B都是指现在的情况；shouldn't have gone表示“本不
应该去二实际上去了”。Couldn'thave gone表示“不可能去过”；故选D。
13.D。用在疑问句中表猜测时，只能用cam.答案为D。
14.C。表推测是，肯定句中可以用may,must,但can 只能用在否定句或疑问句中，故选C。
15.A。May 用在否定句中表推测，意为：“可能不”。
16.D.may,must都可以在肯定句中表推测，但must语气比may肯定，由于前一句用了possible“可能
的”，所以正确答案是D.
17.C。在含有must表推测的句子里，反意问句部分根据must后的动词的相应形式来确定。
18.B。第一句是用来征求意见的，选can和may都行，但第二句强调“必须首先完成作业”，因此只
能选must.。
19.B。含may的一般问句的否定答语应用mustn't。
20.A。含must的一般问句的否定答语不可用mustn't，而要用needn't或don't have to.
21.D.need作情态动词时常用在肯定句或否定句中，并且其后需加动词原形；need作及物动词时，后
面需接带to的不定式，故选D，此时need用作情态动词。
22.C。此题中need用作及物动词，用法21题。
23.A。Had better意思是“最好......”，是一种固定形式，其后接动词原形，其否定形式为had better+not+
动词原形，所以选A。
24.B。Should作情态动词，表示劝告或建议，意思是“应该”，不能看着是shall的过去式用法。
25.D。含有need的一般问句的否定回答应用needn't，但肯定回答却要用must。
26.A。Could这儿不是can 的过去式。而是用作一般现在时中表示委婉的请求。
27.D。此句强调“客观”上不得不干某事，而且是发生在过去的事情。故选D。Must强调“主观”上必须干某事。
28.B。"can (or could)+have+过去分词"这一结构的否定或疑问形式表示对过去发生情况或行为的不肯定或怀疑，故选B。
29.D。"must+have+过去分词"这一肯定结构形式表示对过去已经发生情况的推测，判断。
30.A。"needn't have+过去分词"这一结构表示本来不必要做某事而实际又做了某事。
31.D。"should+have+过去分词"这一结构表示过去应该做某事而实际没有做到，深含责备之意（无论
自责还是责备他人）。
32.B。从题意来看，是对已经发生情况的推测，判断，而且要用被动结构，故选B。
情态动词的考点
湖南高考英语情态动词考点回顾：
〖06湖南〗Some aspects of a pilot’s job___be boring, and pilots often_____work at inconvenient hours.
A.can; have to B.may; can C.have to; may D.ought to; must〖07湖南〗The biggest problem for most plants, which_____just get up and run away when threatened, is that animals like to eat them.
A. shan’t B. can’t C. needn’t D. mustn’t 考点：
〖08湖南〗You don’t have to know the name of the author to find a book.You ______find the book by the title.
A. must B. need C. can D. would考点：〖09湖南〗— It’s the office! So you know eating is not allowed here.
— Oh, sorry.
A. must B. will C. may D. need考点：
〖10湖南〗You______ buy a gift, but you can if you want to.
A. must B. mustn’t C. have to D. don’t have to 考点：
【2011湖南卷,28】No one ________ be compared with Yao Ming in playing basketball.
A. can B. need C. must D. might考点： 总结考点：1：情态动词的基本用法 2. 情态动词表推测
情态动词的试题回顾一： 【考例1】We hope that as many people as possible join us for the picnic tomorrow.
A.need B.must C.should D.can 考点：
【考例2】If it were not for the fact that she sing，I would invite her to the party.
A.couldn’t B.shouldn’t C.can’t D.might not 考点：
【考例3】The World Wide Web is sometimes jokingly called the World Wide Wait because
A.should B.must C.will D.can 考点：
【考例4】You be hungry already— you had lunch only two hours ago。
A.wouldn’t B.can’t C.mustn’t D.needn’t考点：【考例5】Someone is knocking at the door.Who __it be?
A.may B.must C.will D.can 考点：【考例6】How ________ you say that you really understand the whole story if you have covered only part of the article?（03上海卷，29）
A. can B. must C. need D. may 【考例7】I _______ thank you too much for all your help to my son while we were away from home.
A. won’t B. can’t C. can D. will 考点： 归纳：
can（could）
1.表能力，在肯定句中指过去做某事的能力，泛指一般能力用could,只表具备做某事的能力，但并不表明是否干成。如：If I could plan to do anything I wanted to, I’d like to go to Tibet and travel through as much of it as possible. 注意：①be able to 强调经过努力、克服困难等完成某事；则was/were able to表示过去经过努力等成功的做成了某事；
2.表惊讶等感情色彩，仅用于疑问句、否定句和感叹句中。如：
How can you say that you really understand the whole story if you have covered only part of the article?
3.表推测，常不用于肯定句中，若用于肯定句中则表偶尔一时的特征，译作“有时会”；而can’t表不可能。如：
The World Wide Web is sometimes jokingly called the World Wide Wait because it can be very slow. -----Isn’t that Ann’s husband over there?
-----No, it can’t be him. I’m sure he doesn’t wear glasses.
4.表许可，在请求对方许可时，can 在口语中常用；在准许对方做某事时，答语用can,不用could。如：A left-luggage office is a place where bags can be left for a short time, especially at a railway station.
------Could I borrow your dictionary?
-----Yes, of course you can.
（5）能不能。。。，要不要。。。（用于疑问句，表示客气的请求、提议）
Can you give me a lift to the station?
Can’t you lend me 10 dollars？请你借给我10美元吧？
（6）构成下列特殊句式：
①can not/ can never...too...或cannot...enough...“无论怎么。。。也不过份； 越。。。越好 ；非常。。。” One cannot be too carefull. 越认真越好。
②cannot help doing.../ cannot help but do.../ cannot but do...”“禁不住；不由得；不得不”
When a close friend dies, you cannot feel but sad. 当一个密友死的时候 ， 你会禁不住伤心的.
(7) can 还可以用于一般疑问句和否定句表示推测？someone is knocking. Who can it be ? 而在肯定
句中表推测要用must和may
【2012全国卷II】⒘ I’m going to Europe on vacation together with John if I ___ find the money. A. can B. might C. would D. need
1．There’s no light on—
A.can’t B.mustn’t C.needn’t D.shouldn’t ，I’d like to go to Tibet and travel through as much of it as possible.
A.would B.could C.had to D.ought to
3. It is usually warm in my hometown in March，but it A.must B.can C.should D.would
A.shall B.should C.can D.must
5. The importance of saving gas be stressed too much.Automobiles use up some 70 billion gallons of gas a year.
A.shouldn’t B.mustn’t C.cannot D.may not
6. Even if you are an experienced teacher，make some mistakes.
A.can B.must C.should D.will
7.-Look,it ____be Tom.
-No,it _____be him.He has gone to Beijing. A.may,mustn't B.must,may C.must,can't D.can,may not
情态动词的试题回顾二：
【考例1】-Must I turn off the light now?
-No. you ____.
A.needn't B. mustn't C. can't D. won't 考点：
【考例2】Children under 12 years of age in that country be under adult’s supervision when in a public library.
A.must B.may C.can D.need 考点：
【考例3】. Tom，you leave all your clothes on the floor like this!
A.wouldn’t B.mustn’t C.needn’t D.may not 考点：
【考例4】【2012重庆】-___ _you interrupt now? Can’t you see I’m on the phone?
-Sorry Sir, but it’s urgent.
A. Can B. Should C. Must D. Would 【考例5】Naturally，after I have told her what to do，my daughter go and do the opposite!
A.may B.can C.must D.should 考点：
【考例6】. ---What’s that terrible smell ---Oh，I forgot about the chicken!Go and look，it !
A.may be burnt B.ought to be boiling C.can be cooking D.must be burning 考点： 归纳：
must
(1) 必须、得、要（表义务、必要性、命令）Animals must eat to live.(为了活下去，动物必须吃东西。) ---Must I washing the sidhes at once?
---No, you needn’t.. / yes , you must
注： mustn’t 表示“禁止、不准”。Eg: You mustn’t play with the knife; you might hurt yourself.
(2) 必定（表必然性）。 Everyone must die. 每个人都必定会死。
（3）偏偏、偏要、硬要（表固执、不满等）：If you must know, I’m going to help him look for an apartment.
如果你偏要知道，那我告诉你，我要去帮他找一套公寓。
（4）想必、一定、准是（表推测，只用于肯定句）。 He must be ill. He looks so pale.
(5) must 的否定回答用： No, you needn’t/ No, you don’t have to
1. — Could I have a word with you，mum? — Oh dear，A.can B.must C.may D.should
2. John，look at the time. you play the piano at such a late hour?
A.Must B.Can C.May D.Need
3. In crowded places like airports and railway stations， take care of your luggage. A.can B.may C.must D.will
情态动词的试题回顾三：
【考例1】-----Excuse me. Is this the right way to te Summer Palace?
------Sorry, I am not sure. But it ______ be.（04湖北卷，26）
A. might B. will C. must D. can 考点：
【考例3】 Liza ___ well not want to go on the trip --- she hates traveling.（08全国卷II，17）
A. will B. can C. must D. may考点：【考例4】 Although this ____ sound like a simple task, great care is needed.（08四川卷，10）
A. must B. may C. shall D. should 考点：【考例5】- _____ I watch TV this evening?
- Yes,but you ______ finish your homework first.
A.Must;can B. May;must C. Must;may not D. Must,can't考点：
【考例6】-____I sleep here?
-No,you ___.
A.May;needn't B. May;mustn't C. Can;need D. May;may考点：
归纳：
may/ might
(1) 可以。。。（表准许、请求） eg: You may go home now, Susan. 苏珊，你现在可以回家了
表许可：在请求对方许可时，may较正式，might较may委婉；在准许对方做某事时，答语用may,而不用might。如：
-----I hear you’ve got a set of valuable Australian coins. May I have a look?
-----Yes, certainly.
(2) 但愿；祝。。。(表愿望、祝福；此时，句子要用倒装语序) May you succeed.祝你成功。
(3) 为了，为了能够（用于目的状语从句so..that.../ such....that....）
He works hard so that he may get good grade.
(4) 即使，无论（用于让步状语从句中） Whatever he may say, I don’t believe him.
(5) 构成句型 may as well do sth/ might as well do sth (不妨去做某事，还是做某事的好)
(6) May 的否定回答不用may，
---May I use your bike?
---No, you mustn’t/ You’d better not. / please don’t (肯定：Yes, please. / Certainly)
2.表推测，might比may更不肯定；may not，表“可能不”。如：
------Excuse me. Is this the right way to the Summer Palace?
------Sorry, I am not sure. But it might be.
You might just as well tell the manufacture that male customers may not like the design of the furniture. 练习： 1 Although this sound like a simple task，great care is needed
A.must B.may C.shall D.should2. Helen go on the trip with us，but she isn’t quite sure yet.
A.shall B.must C.may D.can
3. Some people who don’t like to talk much are not necessarily shy；A. must B. may C. should D. would
【2012四川】19. I got close enough to hear them speaking Chinese, and I said “Ni Hao ” just as I ____ do in China.
A. must B. might C. can D. should
情态动词考题回顾四：
【考例1】-----What’s the nurse?
-----Khulaifi. _____ I spell that for you?
A. Shall B.Would C. Can D. Might 【考例2】-----Excuse me, but I want to use your computer to type a report.
-----You ______ have my computer if you don’t take care of it.（04湖南卷，28）
A. shan’t B. might not C. needn’t D. shouldn’t
【考例3】-----What does the sign over there read?
------“No person _______ smoke or carry a lighted cigarette, cigar or pipe in this area.”
A. will B. may C. shall D. must 考点：
归纳：
shall
(1) 用于第一、第三人称，表示征求对方意见，请求指示等：Shall we go out for a walk?
注：may 征求对方的许可，而shall是征求对方意见
May I have a look?我能看一下嘛？？Shall I have a look? 要我看一下嘛？？
(2) 用与第二、第三人称，表示说话人的命令、警告、强制、允诺、威胁或决心等：
eg：He shall be sorry one day, I tell you. 我告诉你，他早晚有一天会后悔的（警告）
Don’t worry. You shall get the answer this very afternoon. (允诺)。
Nothing shall stop us from carrying out the plan. (决心)
应。。。/须。。/ 得。。(用于法律、规则等条文中)： The fine shall be given in cash.罚款应以现金
（3）.其否定形式shan’t表禁止或威胁。如：
----Excuse me, but I want to use your computer to type a report.
----You shan’t have my computer if you don’t take care of it.
【2012辽宁】24. One of our rules is that every student ____ wear school uniform while at school.
A. might B. could C. shall D. will
情态动词考例回顾五：
【考例1】------How is your tour around the North Lake? Is it beautiful?
-------It ______ be, but it is now heavily polluted. (07全国卷I,27)
A. will B. would C. should D. must
【考例2】------Turn off the TV, Jack. _______ your homework now?
-------Mum, just ten minutes, please.（07辽宁卷，30）
A. Should you be doing B. Shouldn’t you be doing
C. Couldn’t you be doing D. Will you be doing 考点：
【考例3】 What do you mean, there are only ten tickets? There be twelve
A. should B. would C. will D. shall should
(1) 应该（表义务、责任） ：We should attend the meeting .我们应该参见这次会议。
（2）应该会、想必会、一定会（表预期）：The concert should be great fun. 音乐会一定很有意思。
I should pay Tracy a visit, but I’m not sure whether I will have time this Sunday.
3 .表推测，should not表“也不应该”，为否定推测，而should为肯定推测，表“也按道理应该”。 There shouldn’t be any difficulty about passing the road test since you have practiced a lot in the driving school.
It’s nearly seven o’clock, Jack should be here at any moment.
情态动词考题回顾六：
【考例1】------We have booked a room for today and tomorrow.
-------________ sir.（07全国卷II，7）
A. I’m sure. B. My pleasure C. It’s right. D. I’ll check.
【考例2】------Mr. Gordon asked me to remind you of the meeting this afternoon. Don’t forget it! ------OK. I _______.
A. won’t B. don’t C. will D. do
【考例3】Turn on the television or open a magazine and you ______ advertisements showing happy families. (04湖南卷，25)
A. will often see B. often see C. are often seeing D. have often seen
【考例4】 John promised his doctor he ________ not smoke, and he has smoked ever since.（08北京卷，
A. might B. should C. could D. would.
will
(1) 表意愿，用于各种人称陈述句：If you will read the book, I’ll lend it to you. 如果你愿意读这本书。。。
（2）表请求，用于疑问句：Will you close the door? It is a bit cold.
(3) 表示某种倾向或习惯性动作：The door won’t open.(这门打不开) Fish will die out of water.
(4) 表命令、叮嘱： No one will leave the examination room before 12 o’clock.12点前谁也不得离开考场。
（5）表猜测：That will be the postman at the door. 门口想必是邮差。
would
(1) 常常、经常（表过去的习惯性动作）：We would stay up all night talking our future.
区别：used to ____________________________________________________________
(2) 老是、（表示说话者的厌烦、焦躁）：That’s exactly like Susie. She would come to me just when I was busy.苏西就是那个样子，她老是在我忙碌的时候来找我。
（3）就是（不能）（用于否定句，主语一般是物，表某物一时的、暂时的特性）That door wouldn’t open.
(4) 表示客气的请求、建议；或婉转的表达个人的想法、看法：Would you mind if I open the window?
1.We had to make the corrections by hand as the computer do them for us.（08四川延考区，12）
A. mightn’t B. needn’t C. shouldn’t D. wouldn’t
【2012江苏】28. Days later, my brother called to say he was all right, but ____ say where he was.
A. mustn’t B. shouldn’t C. wouldn’t D. mightn’t
have to (would rather+do)
have to和must的意义相近，只是 must侧重表示说话人的主观看法，而have to 则表示客观需要，如：I must study hard. I had to give it up because of illness.
11. need 和 dare
这两个词都即可用作情态动词， 也可用作实义动词。
① 用作情态动词，主要用于否定句和疑问句； 用作实义动词，主要用于肯定句（当然也可以
用于否定句等）
② 用作实义动词：You needn’t do it yourself.=You don’t need to do it yourself.
I need to tell them the news.
③ need的主语是物时，其后的动词可以是：doing或to be done.“需要”
The table needs painting. = The table needs to be painted.
④ dare 在否定句中，用作实义动词时，其后的to可带，也可以不带。
He did not dare (to) look up. 他不敢抬头看。
⑤ I dare say.... 为固定习语，意思是“我敢说。。。。”
情态动词考点二：表推测
表示对目前或将来情况的推测往往用“情态动词＋动词原形”这种结构。
1．can用于肯定句中有时可以用来表示推测，意为“有时会”；用于疑问句中可以表示推测，意为“可能”，有时表示一种惊讶的语气；用于否定句中也可以表示推测，can’t 意为“不可能”，语气很强烈。
Mr.Bush is on time for everything.How can it be that he was late for the meeting?
布什先生做什么事情都很准时，他怎么可能开会迟到呢？
The story can’t be true. 这个故事不可能是真的。
2．may用于肯定句中可以用来表示推测，意为“可能”；用于否定句中也可以表示推测，may not意为“可能不”，表示一种不太确定的语气。may在疑问句中不能表示推测。
Peter may come with us tonight，but he isn’t sure yet. 彼得今晚可能和我们一起来，但他还没确定。
3．must 表示推测时只能用于肯定句中，意为“一定，必定”，表示十分肯定的语气(在疑问句中或否定句中要用can)。
He must be ill.He looks so pale. 他准是病了，他的脸色苍白。
—It’s the office！So you must know eating is not allowed here. —Oh，sorry.
“这是办公室！所以你一定知道这里不许吃东西。”“噢，对不起。”
4．should 用来表示推测时意为“应该”，即含有“按道理来说应当如此”的意思。
There shouldn’t be any difficulty about passing the road test since you have practiced a lot in the driving school. 因为你在驾校训练了那么多，通过路考应该没什么困难。
-----I think I’ll give Bob a ring.
------You ______ . You haven’t been in touch with him for ages.
A. will B. may C. have to D. should
5．表示对现在正在发生的事情进行推测要用“情态动词＋be＋现在分词”这种结构。这种结构在高考题中出现的次数不太多，但也提醒考生注意。
My mother must be watering the flowers in the garden now.
现在我母亲一定正在花园里浇花。
The students may be climbing the mountain at the moment.
此刻学生们有可能正在爬山。
基础练习：
1. -shall I tell John about it? -No,you ___________.
A.needn't B.wouldn't C.mustn't D.shouldn't
2. Peter _____come with us tonight. But he isn't very sure yet.
A.must B.can C..may D.will
3 -______ I open the door for you?
-No,thanks.I can manage by myself.
A. Will B. May C. Shall D. Should
4 One ought _______ for what one hasn't done.
A.not to be punished B.to not be punished C.be not to punished D.not be punished
5 The fire spread through the hotel very quickly but everyone ______escape.
A.had to B.would C.could D.was able to
6. A computer _____ think for iself; it must be told what to do.
A.can't B.couldn't C.may not S.might not
7. Tell Tom that he ____have the book next week.
A.shall B.will C.can D.would
8 If you really want yourself to be in good health.you must____always_____so much.
A.not;be smoking B.not;have smoked C.to not;be smoking D.not be;smoked 9 Don't be worried.The news ___ be ture.
A.may not B.mustn't C.needn't D.won't
10 "It's possible that Mr.wu is working now."
The sentence means ______.
A. Mr .Wu must be working now B. Mr . Wu can't be working now
C. Mr . Wu should work now D. Mr .Wu may be working now
11 You ___ so early.
A.need come B.doesn't need come C.needs come D.needn't come
12. We ____ them.They can do it by themselves.
A.need help B.don't need help C.don't need to help D.needn't to help
13. You'd better ___ in class.
A.not talk B.not to talk C.don't talk D.not talking
14. You ____ go with us now,or you will be late.
A.shall B.should C.would D.could
15 - Need I go to work now?
-Yes,you ____.
A.need B.can C.may D.must
16 Could you tell me if there ____plenty of rain in your hometown?
A.is B.would be C.are D.was
17. A boy was crossing the street in front of my car,and I _____ stop very quickly.
A.must B.have to C.has to D.had to
.
A.need repairing B.needs to repair C.needs repairing D.need to repair
情态动词考点三、 情态动词+have done的用法：
情态动词+have done一定表述的是过去的事情，且表示对过去发生的事情的推测、判断，或表某种强烈的语气（如惊讶、责备、赞叹等）
⑴ must + have done 表“过去肯定发生了某事”。The room is clean. Someone must have cleaned it. 注：绝对没有下面的形式：mustn’t have done.
⑵ may/might + have done 表示“过去可能发生了某事”，其中might 的语气要婉转些；但是主句中
动词是过去时，一定要用might, 如He said she might have missed the train.
⑶ could + have done,表示“过去本来能够做成某事，但是没有做到”:You could have succeeded. ⑷ can’t/couldn’t have done 表示“绝不可能发生了某事”：
He couldn’t have taken all the medicine at a time.
⑸ should/ought to +have done, 表示“过去本来应该做某事，但实际上未做”
You are late again. You ought to have come one hour earlier.
⑹ shouldn’t+ have done/ 或oughtn’t to have done, 表示“过去不应该做某事而做了某事”
This is my letter. You shouldn’t have opened it.
⑺ needn’t + have done 表示“本没有必要做某事，而做了”
There was plenty of time, so she needn’t have hurried. 有充足的时间，所以她没有必要哪么急的。。
四、must 表示推测时：其反义疑问句的构成如下：
He must be a teacher, ______________?
She must have finished the work, _____________?
She must have finished the work last night, ______________?
She must have finished the work by the end of last month, ___________?
练习题：
1You mother must be at home,_____ she?
A.mustn't B.doesn't C.isn't D.can't ， for her bike is still here.
A.can’t B.wouldn’t C.shouldn’t D.needn’t
3. What a pity!Considering his ability and experience， he better.
A.need have done B.must have done C.can have done D.might have done
4—I can’t find my purse anywhere. —You have lost it while shopping.
A.may B.can C.should D.would
5. It_____ have been Tom that parked the car here, as he is the only one with a car.
A. may B. can C. must D. should答案 C
6.—I’m sorry.I at you the other day.
—Forget it.I was a bit out of control myself.
A.shouldn’t shou B.shouldn’t have shouted C.mustn’t shout D.mustn’t have shouted
7 Thank you for all your hard work last week.I don’t think we
A.can manage B.could have managed C.could manage D.can have managed
8.-----Where is my dictionary? I remember I put it here yesterday.
-----You _______ it in the wrong place.（07江西卷，27）
A. must put B. should have put C. might put D. might have put
9 ---I can’t find my purse anywhere.---You have lost it while shopping.（08重庆卷，30）
A. may B. can C. should D. would
10-----My cat’s really fat.
-------You ______ have given her so much food.（07浙江卷，15）
A. wouldn’t B. couldn’t C. shouldn’t D. mustn’t
1I told your friend how to get to the hotel, but perhaps I _______ have driven her there.
A. could B. must C. might D.should
12 --- I’m sorry. I ___________ at you the other day. --- Forget it. I was a bit out of control myself.
A. shouldn’t shout B. shouldn’t have shouted C. mustn’t shout D. mustn’t have shouted
13. She _____have had a hard life since she looked much older than her age.
A.may B.may not C.mustn't D.must
14 He went home because his mother was ill.We ____have waited for him at the bus station for a long time.
A.needn't B.need C.must D.shall
15. Mr Wang is wet through.He ___caught in the rain.
A.must be B.must have been C.must has been D.must nave
【2012浙江】19. Had they known what was coming next, they _____ second thoughts.
A. may have B. could have C. must have had D. might have had
[基础训练：答案与解析]
1.A。needn't意为“不必”；wouldn't意为“不会”；mustn't意为“不许或禁止”；shouldn't意为“不应
当”。根据题意，回话人强调对方“不必做......”。故选A.
2.C。Must come表示必须来；can come 能够来；may come 可能来；will come 将要来；根据题意，
说话人的语气表示推测，且不很肯定，故选C.must 表示推测，意为“一定或准是”，只用于肯定句中；can表示推测，意为“可能，或许”，一般用于疑问句或否定句中，但could也可用于肯定句，表示对某事把握不大；may表示推测，意为“或许，可能”，一般英语肯定句或否定句。
3.D。根据题意，说话人对已经发生的事情进行否定推测，故选D。表示对过去发生的事情进行推测，
常用can/may/might/must+have+动词分词。
4.B。此题表示对过去事情的肯定推测，应选B。
5.C。根据语境可知，问句是征求对方意见，故C。
6.A。情态动词ought后接带to的不定式，ought to do的否定式是ought not to do，故选A。
7.D。根据题意，可首先排除A和B。Could表示一种能力；was able to表示在困难的情况下，经过一番周折而“能”。
8.C。Should(ought to) have done sth.表示“过去本应该做某事而没有做到”，含有责备,后悔的意思；
must have done sth.表示对过去动作或行为的推测。根据题意应选C.
9.A。题中的can't是指能为。Couldn't是can't的过去式，这里讲的是一个客观事实，要用一般现在时。
10.A。Shall用于第二，三人称陈述句中表示说话人给对方的命令，警告，允诺，威胁等概念。
11.A。must not always be doing sth.表示“不要老是做某事”，含有埋怨，指责，反感等感情色彩。
12.D。根据题意，本体是谈论过去的事情，A,B都是指现在的情况；shouldn't have gone表示“本不
应该去二实际上去了”。Couldn'thave gone表示“不可能去过”；故选D。
13.D。用在疑问句中表猜测时，只能用cam.答案为D。
14.C。表推测是，肯定句中可以用may,must,但can 只能用在否定句或疑问句中，故选C。
15.A。May 用在否定句中表推测，意为：“可能不”。
16.D.may,must都可以在肯定句中表推测，但must语气比may肯定，由于前一句用了possible“可能
的”，所以正确答案是D.
17.C。在含有must表推测的句子里，反意问句部分根据must后的动词的相应形式来确定。
18.B。第一句是用来征求意见的，选can和may都行，但第二句强调“必须首先完成作业”，因此只
能选must.。
19.B。含may的一般问句的否定答语应用mustn't。
20.A。含must的一般问句的否定答语不可用mustn't，而要用needn't或don't have to.
21.D.need作情态动词时常用在肯定句或否定句中，并且其后需加动词原形；need作及物动词时，后
面需接带to的不定式，故选D，此时need用作情态动词。
22.C。此题中need用作及物动词，用法21题。
23.A。Had better意思是“最好......”，是一种固定形式，其后接动词原形，其否定形式为had better+not+
动词原形，所以选A。
24.B。Should作情态动词，表示劝告或建议，意思是“应该”，不能看着是shall的过去式用法。
25.D。含有need的一般问句的否定回答应用needn't，但肯定回答却要用must。
26.A。Could这儿不是can 的过去式。而是用作一般现在时中表示委婉的请求。
27.D。此句强调“客观”上不得不干某事，而且是发生在过去的事情。故选D。Must强调“主观”上必须干某事。
28.B。"can (or could)+have+过去分词"这一结构的否定或疑问形式表示对过去发生情况或行为的不肯定或怀疑，故选B。
29.D。"must+have+过去分词"这一肯定结构形式表示对过去已经发生情况的推测，判断。
30.A。"needn't have+过去分词"这一结构表示本来不必要做某事而实际又做了某事。
31.D。"should+have+过去分词"这一结构表示过去应该做某事而实际没有做到，深含责备之意（无论
自责还是责备他人）。
32.B。从题意来看，是对已经发生情况的推测，判断，而且要用被动结构，故选B。