1、情态动词一 情态动词的概念： 所谓情态动词是指它含有一定的含意可以表达某种感情和说话的口气，但是它不可以单独使用作谓语动词。情态动词有：can(could)，may(might)，must(must)，have to，shall(should)，will (would)，need(need)，dare(dared)，ought to。要注意的是：1).情态动词不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。2).情态动词除ought 和have 外，后面只能接不带to 的不定式。3).情态动词没有人称,数的变化，即情态动词第三人称单数不加-s。4）情态动词没有非谓语形式，即没有不
2、定式，分词等形式。二 . can, could 和be able to 1. cancould表示能力或客观可能性，还可以表示请求和允许。只用于现在式和过去式(could)。be able to可以用于各种时态。如:(1). Can you finish this work tonight? (2). Man cannot live without air(3).Can I go now? Yes，you can.(4).They will be able to tell you the news soon.他很快就能告诉你消息了。2. 只用be able to ：a. 位于助动词后。 b.
3、情态动词后。 c. 表示过去某时刻动作时。 d. 用于句首表示条件。 e. 表示成功地做了某事时，只能用was/were able to， 不能用could。如：He was able to flee Europe before the war broke out. = He managed to flee Europe before the war broke out.3. could也可表示请求。语气委婉主要用于疑问句不可用于肯定句，答语应用Can。 如:1) .- Could I have the television on?- Yes, you can. / No, you cant.
4、 2). -Could I come to see you tomorrow? -Yes, you can . (否定答语可以用No, Im afraid not)在否定，疑问句中表示推测或怀疑。如：He couldnt be a bad man. 他不大可能是坏人。4. 表示惊异怀疑，不相信态度。（主要用在否定旬、疑问句或感叹句中）Can this be true? How can you be so careless! This cannot be done by him5. can (could)+have+过去分词”的疑问或否定形式表示对过发生的行为怀疑或不肯定。例如:He canno
5、t have been to that town Can he have got the book?cant/couldnt可表否定推测。 如：If Tom didnt leave here until five oclock, he cant be home yet.如果汤姆五点才离开这儿，他此时一定还未到家。6. can 习惯用法： cannot but不得不；如：I cannot but admire his courage我不得不佩服他的勇气。 cannot (couldnt) help + doing 情不自禁；如：When I heard what the little girl
6、said I couldnt help laughing当我听见小女孩所讲的，不禁大笑起来。 can but只好，不得不；如： We can but agree with him我们只好同意他。 cannot .too.怎么也不过分；如：You cannot be too careful in the choice of your friends你在选择朋友时，怎么小心也不过分。 三may和might 1表示许可。表示请求、允许时，might比may的语气更委婉一些，否定回答时要用mustnt表示“不可以”、“禁止”、“阻止”之意。例如：You may drive the carMight I
7、 use your pen? No，you mustnt(用May I征询对方许可在文体上比较正式，在口气上比较客气。在日常用语中用Can。)2表示推测、可能(疑问句不能用于此意) He may be very busy now3用于析使句中表示祝愿。May you succeed ！4表示请求或规劝。You might pay more attention to me5“may(might)+have+过去分词”表示对过去发生的行为的推测。例如：He may not have finished the work6May/might的其他用法：may not表示一种礼貌的“不可”。如：You
8、may not leave the thing half donemight可表示忠告，责备。如：Yon have broken two dishesYou might try to be more carefulmay well +原形， 理所当然You may well say so你当然可以这样讲。May/might as well=had better 最好 如：We may as well stay where we are我们最好是留在原处。 If that is the case, we may as well try.May/might as well+原形+as+原形 与其不
9、如； 最好不要；如：You might as well throw your money away as lend it to him你要借给他钱,不如把钱扔了。Peter _come with us tonight, but he isnt very sure yet. A. mustB. may C. can D. will四。 have to和must 1. must表示必须，强调的是一种主观看法。也表示责任或义务而have to表示必须时强调的是客观需要。have to可以用在更多的时态中。My brother was very ill, so I had to call the do
10、ctor in the middle of the night.我弟弟病得很厉害，我只得半夜里把医生请来。(客观上需要做这件事)He said that they must work hard.他说他们必须努力工作.（主观上要做这件事） You must obey the rules(责任或义务)You will have to do it again你将不得不再做一次。回答must引出的问句时如果是否定的回答不能用mustnt而要用neednt或dont have to。如： Must we hand in our exercise books today?Yesyou must(Noyou
11、 dont have to)2 “must be+表语”的结构表示推测。它的否定或疑问形式用can代替must。This must be your pen3must+have+过去分词”的结构常用在肯定句中表示对过去发生的行为的推测。它的否定或疑问形式用can代替must。He must have been to Shanghai4 .must一般只表现在，have则有更多的时态形式。5.二者的否定意义不大相同Mustnt表“禁止”, dont have to(=neednt)表没有必要。例如： Yon mustnt go你可不要去。You dont have to go你不必去。6询问对方的
12、意愿时应用must。例如： Must I clean all the room?五 will和would 1. 表示请求、建议等，would 比will委婉客气. Would you pass me the salt?2表示意志、愿望和决心。I will never do that again.They asked us if we would do that again.3表示习惯动作。 Fish will die without water.4表示预言。Oil will float on water5用“will be”和“will十have十过去分词”的结构表示推测，主要用于第二、三人称
13、。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 wantHe will have arrived by now6Would可表示过去反复发生的动作或某种倾向。would表过去习惯时比used to正式。并没有“现已无此习惯”的含义。The wound would not healDuring the vacation he would visit me every week7表料想或猜想。It would be about ten when he left homeWhat would she be doing there?
14、I thought he would have told you all about it8would like； Would like to do = want to 想要，为固定搭配。 Would you like to go with me?9. Will you?Would you like? 表示肯定含义的请求劝说时，疑问句中一般用some, 而不是any。 Would you like some cake?10. 否定结构中用will，一般不用would, wont you是一种委婉语气。 Wont you sit down?六Shall, should 和ought to1. s
15、hall用于第一人称表示征求对方的意见： What shall we do next?2. shall用于第一、第三人称疑问句中表示说话人征求对方的意见或向对方请示。Shall we begin our meeting? When shall we leave the hospital?3. shall用于第二 、第三人称，表示说话人给对方的命令、警告、允诺或威胁。You shall fail if you dont work harder(警告) ; He shall have a book when I finish reading (允诺); He shall be punished(威
16、胁) 4. 表示推测或可能。 They should finish the work by now.5. should表示劝告、义务、建议、命令，其同义词是ought to；在疑问句中。通常用should代替ought to。We should learn some English. You should go to class right away. Should I open the window?注意： should的含义较多，用法灵活。现介绍三种其特殊用法。请看下面句子： I should think it would be better to try it again.我倒是认为最好
17、再试一试。 You are mistaken. I should say.依我看，你是搞错了。I should advise you not to do that我倒是劝你别这样做。This is something I should have liked to ask you.这是我本来想问你的。从以上例句可以看出：情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。此外,Why / How_+ should结构表示说话人对某事不能理解，感到以外、赞叹、愤怒、惊异等感情，意思为“竟会”。例如：Why should you be so late today? 你今天怎
18、么来这么晚？-Where is Betty living? Betty住哪儿？ -How should I?我怎么回知道。I dont know why you should think that I did it.我真不知道你凭什么认为这件事是我干的。6. should表示允许。It should be ready at noon.7. should +have +过去分词, 表示应该做而实际上没有做到. You should have started earlier.8. should 和ought to 都为应该的意思，可用于各种人称。-Ought he to go?-Yes. I th
19、ink he ought to. 9. 表示要求，命令时，语气由 should（应该）、had better最好）、must（必须）渐强。七need和dare1need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：You neednt come so early-Need I finish the work today? -Yes，you must / No, you neednt.注意neednt+不定式的完成式，表示本来不必做某事而实际上做了某事。You neednt have waite
20、d for me2dare作情态动词时，主要用于疑同句、否定句和条件从句中，一般不用在肯定句中。How dare you say Im unfairHe darent speak English before such a crowd, dare he?3dare和need常作实义动词。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，dare后面常接带to的不定式。在否定和疑问同中，dare后面可接带to或不带to的不定式。I dare to swim across this river He does not dare(to)answer Dont you dare(to)touc
21、h it! I wondered he dare(to)say that He needs to finish it this evening4. need 的被动含义：need, want, require, worth（形容词）后面接doing也可以表示被动：need doing = need to be done八 had better表示最好 1 . had better 相当于一个助动词，它只有一种形式，它后面要跟动词原形。had better do sth ；had better not do sth 如：It is pretty cold. Youd better put on
22、my coat.Shed better not play with the dog. 2. had better have done sth表示与事实相反的结果，意为本来最好。You had better have come earlier.九 would rather表示宁愿 would rather do；would rather not dowould rather than 宁愿而不愿。 还有would sooner, had rather, had sooner都表示宁愿、宁可的意思。If I have a choice, I had sooner not continue my s
23、tudies at this school.I would rather stay here than go home. = I would stay here rather than go home.- Shall we go skating or stay at home? -Which _ do? A. do you rather B. would you rather C. will you rather D. should you rather十情态动词的回答方式 问句肯定回答否定回答Need you?Yes, I must.No,I needntMust you?/dont hav
24、e to. 1）-Could I borrow your dictionary?-Yes, of course, you_. A. mightB. will C. can D. should 答案C. could表示委婉的语气，并不为时态。答语中of course，表示肯定的语气，允许某人做某事时，用can和 may来表达，不能用could或might。2）-Shall I tell John about it?-No, you _. Ive told him already. A. needntB. wouldntC. mustntD. shouldnt 答案A。neednt 不必，不用。
25、wouldnt 将不, 不会的。 mustnt 禁止、不能。 shouldnt不应该。本题为不需要，不必的意思，应用neednt。3）-Dont forget to come to my birthday party tomorrow.-_.A. I dont B.I wont C. I cantD. I havent 答案B.will既可当作情态动词，表请求、建议、也可作为实义动词表意愿、意志、决心，本题表示决心，选B。十一。带to 的情态动词 带to 的情态动词有四个：ought to, have to, used to, be to, 如加上have got to ,(=must), b
26、e able to，为六个。它们的疑问，否定形式应予以注意： Do they have to pay their bill before the end of the month? She didnt use to play tennis before she was fourteen. You ought not to have told her all about it. Ought he to see a heart specialist at once.? ought to 本身作为情态动词使用。其他的词作为实义动词使用，变疑问，否定时，须有do 等助动词协助。如：Tom ought
27、not to _ me your secret, but he meant no harm. A. have toldB. tellC. be tellingD. having told答案A。由于后句为过去时，告诉秘密的动作又发生在其前因，此地应用过去完成时，但它在情态动词 ought to 后，所以用 have。十二。情态动词+ have +过去分词 1) may(might) have + done sth, can (could) have + done sth表示过去，推测过去时间里可能发生的事情。Philip may (might) have been hurt seriously
28、 in the car accident.Philip can (could) have been hurt seriously in the car accident.2)must have +done sth，对过去时间里可能发生的事情的推测，语气较强，具有肯定，谅必的意思。- Linda has gone to work, but her bicycle is still here. -She must have gone by bus.3) ought to have done sth, should have done sth本应该做某事，而事实上并没有做。否定句表示不该做某事而做了
29、。You ought to (should) have been more careful in this experiment.He ought not to have thrown the old clothes away.（事实上已扔了。） ought to 在语气上比should 要强。4) neednt have done sth 本没必要做某事I dressed very warmly for the trip, but Ineednt have done so. The weather was hot.5) would like to have done sth 本打算做某事I
30、would like to have read the article, but I was very busy then.1. He_you more help, even though he was very busy. A. might have given B. might give C. may have given D. may give2. Jenny_have kept her word. I wonder why she changed her mind. A. must B. should C. need D. would3. . -Could I borrow your
31、dictionary? -Yes, of course you_ A. mightB. will C. canD. should 4. I told Sally how to get here, but perhaps I _ for her. A. had to write it out B. must have written it out C. should have written it out D. ought to write it out5. Shall I tell John about it?No, you _ . Ive told him already. A. needn
32、t B. wouldnt C. mustnt D. shouldnt6. There were already five people in the car but they managed to take me as well. It_a comfortable journey.A. cant be B. shouldnt beC. mustnt have been D. couldnt have been7. Its nearly seven oclock. Jack_be here at any moment.A. must B. need C. should D. can8. .Whe
33、n he was there, he_ go to that coffee shop at the corner after workevery day. A. would B. should C. had betterD. might9. .Sir, you _ be sitting in this waiting room. It is for women and children only. A. oughtnt to B. cant C. wont D. neednt10. The fire spread through the hotel very quickly but every
34、one _ get out. A. had toB. wouldC. couldD. was able to11. -When can I come for the photos? I need them tomorrow afternoon. -They _be ready by 12:00. A. can B. should C. might D. need12. .-I stayed at a hotel while in New York.-Oh, did you? You_ _with Barbara. A. could have stayed B. could stay C. wo
35、uld stayD. must have stayed13. Will you stay for lunch? Sorry, ,My brother is coming to see me. A. I mustnt B.I cant C. I neednt D.I wont14. Sorry Im late. I _ have turned off the alarm clock and gone back to sleep again. A. mightB. shouldC. can D. will15. I should have been there, but I _ not find
36、the time. A. would B. couldC. mightD. should 16. My sister met him at the Grand Theatre yesterday afternoon, so he _ your lecture. A. couldnt have attendedB. neednt have attended C. mustnt have attendedD. shouldnt have attended17. - Are you coming to Jeffs party? - Im not sure. I _go to the concert
37、instead.Amust Bwould Cshould Dmight18. Mr. Bush is on time for everything. How _ it be that he was late for the opening ceremony? Acan Bshould Cmay Dmust19 He hesitated for a moment before kicking the ball, otherwise he _ a goal. Ahad scored Bscored Cwould score Dwould have scored20. Write to me whe
38、n you get home. _ AI mustBI should CI willDI can21. I was really anxious about you. You _ home without a word. A. mustnt leave B. Shouldnt have left C. Couldnt have left D. neednt leave22. Oh, Im not feeling well in the stomach, I_so much fried chicken just now.A. shouldntt cut B. mustntt have eaten
39、C. shouldntt have eaten D. mustntt eat23. -I heard they went skiing in the mountains last winter.-It _ be true because there was little snow there. A .may not be B. wont be C .couldnt be D. mustnt be24. It has been announced that candidates_ remain in their seats until all the papers have been colle
40、cted. A can B will C may D shall25.A left-luggage office is a place where bags _ be lefe for a short time, especially in a railway station. A. should B. can C. must D. will26. - I dont mind telling you what I know. - You . Im not asking you for it.A. mustnt B. may not C. cant D. neednt27. I often se
41、e lights in that empty house. Do you think I _ report it to the police?A. should B. may C. will D. can28. Mr.White _ at 8:30 for the meeting, but he didnt show up.A. should have arrived B. should arriveC. should have had arrived D. should be arriving29. You _ be tired - youve only been working for an hour.A. must not B. won t C. can t D. may not30. Who is the girl standing over there ? Well , if you know , her name is Mabel. A. may B. can C. must D. shallKeys:1-5 ABCCA 6-10 DCAAD11-15 BABAB 16-20 ADADC21-25 BCCDB 26-30 DAACC
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