情态动词讲解课件ppt.ppt

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1、-Modal Verbs语法语法 ：情态动词：情态动词I 情态动词的定义情态动词的定义 情态动词是一种本身有一定的词义，表示说话人的情绪、态度或语气的动词，但不能单独作谓语，只能和其他动词原形构成谓语。 情态动词数量不多，但用途广泛，主要有： can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) . 情态动词情态动词 Modal VerbsII 情态动词的位置情态动词的位置情态动词在句中放在谓语动词之前，谓语动词前若有助动词，则在助动词之前，疑问句中， 情态动词放在主

2、语之前。 I can see you. Come here. 我能看见你，过来吧。 He must have been away. 他一定走了。 What can I do for you? 你要什么？ How dare you treat us like that! 你怎么敢那样对待我们! 情态动词的语法特征情态动词的语法特征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，后面只能接动词原形。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，即没有不定式，分词，等形式。 情态

3、动词的用法can和和could情态动词情态动词 用用 法法 例例 句句can/could1“I dont think Mike can type.” “Yes, he can.”2I can speak fluent English now , but I couldnt last year.Can the man over there be our head master?1.Can we turn the air conditioner on?2.In soccer, you cant touch the ball with your hands.3.Could you have her

4、call me back when she gets home, please?4.I wonder if I could just ask you to sign this. 1.As a human being, anyone can make a mistake. 2.Im confident that a solution can be found. 3.A gas can be turned into a liquid.1.Can this be an excuse for not giving them help?2.This cant be true.3.How can you

5、be so crazy.1.How can you believe such a liar like him?表示能力表示请求和允许。表示请求，口语中常用could代替can，使语气更委婉。表示惊异、怀疑、不相信等态度，主要用在否定句、疑问句和感叹句中。在肯定句中，表示客观可能性，常用来说明人或事物的特征（译为“有时会”）。要表达具体某事实际发生的可能性时，不用can，需用could，may，might。 表示对现在的动作或状态进行主观的猜测，主要用在否定句和疑问句中。特别说明：特别说明：1.could用来表示请求时，语气委婉，主要用于疑问句，不能用于肯定句，答语应用can（即：could不能

6、用于现在时态的简略答语中）。如：Could I use your dictionary?Yes, you can.(否定回答可用：No, Im afraid not.或者是you cant)2.表示推测时，could不是过去式，只是语气更委婉；若是推测已发生的事或过去的情况，用can/could have done3.can和be able to辨析can(could)和be able to都可以表示能力，意思上没有区别。但can只有现在式和过去式，而be able to则有更多的形式。如： Ive always wanted to be able to speak fluent Englis

7、h. Those bags look really heavy, are you sure youll be able to carry them on your own?但是，表示在过去某时的某一场合经过一番努力，终于做成了某事，通常不用could，而用was/were able to来表示。这时，was/were able to相当于managed to do或succeed in doing。如： After the accident it was a long time before she was able to walk again. The fire was very big,

8、but most people were able to escape from the building.4 惯用形式“cannot too”表示“无论怎么也不（过分）”。如：You cannot be too careful.你越小 心越好。 惯用形式“cannot but+ 不定式（不带to）”表示“不得不，只好”。如：I cannot but admire her determination. 我不得不钦佩你的决心。 二二may和和 might情态动词情态动词用法用法例句例句may/might1.May I come in and wait?2.May I smoke here?No,

9、 you mustnt(或No, youd better not.)1.Might I borrow your pen2.I wonder if I might speak to your son.1.It may rain this afternoon.2.She might come to join us this afternoon.3.I suppose he might have missed the train.1.May you succeed.2.May you live happily!3.May she rest in peace.愿她安息。1.There is nothi

10、ng to do, so I may as well go to bed.2.You may as well tell us now, well find out sooner or later.3.I suppose we might as well go home.表示允许、许可。否定回答一般用must not/mustnt,表示“禁止、阻止”之意，但也可以用had better not (最好别)或may not（不可以），语气较为委婉。在表示请求、允许时，might比may语气更委婉些。用May I征询对方许可在文体上比较正式，在日常用语中，用Can I征询对方意见更为常见。表示可能性

11、的推测，通常用在肯定句和否定句中，含有“或许”“大概”“可能”之意；用might代替may时，则语气显得更加不肯定。may用于祈使句表示祝愿惯用句式：“may as well或might(just)as well+动词原形”意为“最好，满可以，倒不如”，相当于“had better.1.A computer _ think for itself; it must be told what to do. A. cant B. couldnt C. may not D. might not1.I thought you _ like something to read, so I have bro

12、ught you some books. A. mayB. mightC. couldD. mustmay, might, can, could1. They (can/might) _be away for the weekend but Im not sure.2. You (may/might) _leave now if you wish.3. (could/may) _you open the window a bit, please?4. He (can/could) _be from America, judging by his accent.5. (may/can) _you

13、 swim?6. Listen, please. You (may not/might not) _ speak during this exam.might表示猜测表示猜测may表示许可表示许可could表示请求表示请求could表示猜测表示猜测can 表示能力表示能力may not表示不允许表示不允许may, might, can, could7. They (can not/may not) _ still be out, the light is on in the house.8. You (couldnt/might not) _ smoke on the bus.9. With

14、luck, tomorrow (can/could) _be a cooler day.10. You (can/might) _ be right, but Im going back to check it.表示许可表示许可couldntcould表示猜测表示猜测can not表示猜测表示猜测(不可能不可能)might表示猜测表示猜测三三must和和have to情态动词情态动词用法用法例句例句must1.You must come to school on time.2.Everybody must obey the law.3.You mustnt drive so fast in t

15、he street.4.We mustnt waste any more time.1Must I come back before ten? Yes，you must. -No, you neednt(No, you dont have to)1.It must be my mother.2.You must be hungry after a walk.3.There must be a hole in the wall. have to1.The film is not interesting. I really must go now.2.I have to go now, becau

16、se my mother is in hospital.1I had to work hard when I was your age.2I will have to learn how to use acomputer.3In order to take the exam, well have to finish the whole book by the end of this month .1.You mustnt go there.2.You dont have to go there.表示表示“必须，应该必须，应该”之意，语气比之意，语气比should，ought to强烈。其否定形

17、式强烈。其否定形式mustnt表示表示“不不准，不应该，禁止准，不应该，禁止”等意等意在回答带有在回答带有must的问句时，否定回答常用的问句时，否定回答常用neednt或或dont have to，表示，表示“不必不必”，而不用而不用mustnt表示有把握的推测，意为表示有把握的推测，意为“一定、准一定、准是、相必是、相必”，只用于肯定句中，只用于肯定句中“必须，不得不必须，不得不”，意义与，意义与must相近。但相近。但must表示的是说话人的主观看法，而表示的是说话人的主观看法，而have to则往往强调客观需要。则往往强调客观需要。must只有一种形式，即现在式与过去式都是只有一种形式

18、，即现在式与过去式都是一种形式，而一种形式，而have to则涉及各种人称、时态则涉及各种人称、时态等方面的变化形式。等方面的变化形式。两者的否定意义不同，两者的否定意义不同，mustnt表示表示“禁止，禁止，不许不许”，dont have to表示不必。表示不必。注意：表示注意：表示”偏要，硬要做某事偏要，硬要做某事-how old are you, madam?-if you must know, Im twice my sons age.如果你非得知道，是我儿子年龄的两倍四四shall和和should情态动词情态动词用法用法例句例句shall1.Shall I open the wind

19、ow?2.Shall we say 6 oclock, then?3.Shall he come to see you?1.Dont worry, you shall get the answer this afternoon2.He shall be sorry for it one day, I tell you. （3.You shall do as I say. If you children dont do as I tell you, you shall not go to the party. 4.The Persons under 18 shall not be employe

20、d in night work不满十八岁的人不得雇佣干夜间工作。5.That day shall come6.Candidates shall remain in their seats until all the papers have been collected. 试卷完全收回后，应试人才能离开座位。用于第一、三人称构成的疑问句，表示征求对方意见或请求指示,其意为“要不要”、“好吗”：1 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、命令、规定、必然性等2表示强制，用于法令、条约、规章中，意为“必须，应该”。.(允诺)警告）(命令)(威胁)(表规定)(表必然性)sh

21、ould1.What should I do?2.Should I trust him?3.You should read his new book.1.It should be a nice day tomorrow.2.It s nearly 7 oclock .Jack should speak in such a way.3.He should be around sixty years old.1.Ask Tom to ring me up if you should see him. (你万一见到汤姆，请让他给我打个电话)2.Should I be free tomorrow, I

22、ll come. (万一我明天有时间，我就过来)3.If things should change suddenly, please let me know. (万一情况突变，请通知我)1.Its strange that he should come so late. 2.Im sorry that this should have happened. 3.Im surprised that he should say so. Why should anyone want to marry Tony?4.Dont ask me. How should I know?表示劝告或建议，意为“应该

23、”表示推测，用在肯定句中，对现在的情况或可能发生的事的主观推测或期待。意为“想必，理应” 大概。【注】should表示推断时，语气较肯定，通常是指非常可能的事(因为暗示有一定的事实依据或合乎常理)，还可以用在if引导的条件句中，表示一件事听起来可能性很小，但也不是完全不可能，相当于“万一”的意思。从句谓语用should+动词原形构成，主句都一定用虚拟语气1should表示意外或惊讶2用于疑问句或感叹句中，表示意外、惊异的情绪，意为“竟会”，与why，what，how，who连用，如果是疑问句，则不需要回答。1. Its nearly seven oclock. Jack _ be here a

24、t any moment. A. must B. need C. should D. can2. Johnny, you _ play with the knife, you _ hurt yourself. A. wont; cant B. mustnt; may C. shouldnt; must D. cant; shouldnt3.Our house is on the top of the hill, so in summer the wind _ be pretty cold. A. mustB. can C. ought toD. need4. Professor Smith,

25、many students want to see you. _ they wait here or outside? A. Do B. Shall C. Will D. Would五五will和和would情态动词情态动词用法用法例句例句will/would1.He is the man who will go his own way. 2.They said they would meet us at 10:30 at the station.1.Will you please take a message for him?2.Would you please tell me your t

26、elephone number?1.Fish will die without water.2.People will talk. (人们总会说闲话。)3.When we worked in the same office, we would often have coffee together.1.These things will happen.2.That will be the messenger ringing.3.It would be about ten oclock when he left home.1.That will be all right.2.Either pen

27、will do.3.It would not do to work too late.（工作太晚不行。）1I wont listen to your nonsense.2No matter what I said, he wouldnt listen to me.用于表示意志或意愿或决心。will指现在，would指过去。表示请求、建议等和you连用，用would比用will委婉、客气。表示习惯或倾向，意为“总是，惯于”。will至现在，would指过去。表示推测，意为“很可能，大概”。will表示推测比should把握大，比must把握小。表示功能，意为“能，行”。惯用形式：will do/

28、would do表示“解决问题”、“就行”。用于否定句中，意为“不肯”、“不乐意”特别说明：特别说明：would与与used to辨析辨析1 He _ be a naughty boy and cause trouble. 2 I _get up at six in the morning. 3 Sometimes she _take a walk in the neighboring woods. 4 In those days, whenever I had difficulties, I _go to Mr. Chen for help.used toused towouldwouldw

29、ould可用来表示过去反复出现的动作，但不能表示过去存在的状态可用来表示过去反复出现的动作，但不能表示过去存在的状态.另外，另外，would强调过去某种特强调过去某种特定情况下的活动，是完全过去的事情，同现在没有联系。而定情况下的活动，是完全过去的事情，同现在没有联系。而used to则着眼于过去和现在的对比，隐则着眼于过去和现在的对比，隐含现在已不存在，动作或状态都可表示。含现在已不存在，动作或状态都可表示。Would可以表示不规则的习惯，可以表示不规则的习惯，used to则不可。则不可。 1. We _ smoke here, because the worker is carrying

30、 some petrol. 2. It is dangerous. You _ leave the room immediately. 3. He _ go hiking with friends at weekends when young. 4. Write to me when you get home.-I _. 5. -Need I hand in my exercise book at once?-Yes, you_. 6. You have been working all day. You _ be very tired. 7. It is a long time since

31、we met last time. You _ come and see us more often. 8. Why dont you try on this dress? It _ look nice on you.will, would, shall, should, must:mustntshouldwouldwillmustmustshouldwill表示禁止表示禁止,不许可不许可表示建议表示建议,命令命令表示过去习惯表示过去习惯表示意愿表示意愿表示必须表示必须表示肯定猜测表示肯定猜测表示建议表示建议表示将会表示将会,一定会一定会六六need和和dare情态动情态动词词用法用法例句例句

32、need1Need we leave soon? Yes, you must.(No, you neednt, or dont have to)2You neednt have hurried.(=It was not necessary for you to hurry，but you did).你当时不必这么匆忙。1. A job like nursing needs patience and understanding.(need+名词，need understanding=need to be understood,需要被理解)2He needs to see a doctor.(ne

33、ed to do)3They didnt need to start so early.(do not need to do)dare1Dare you tell her the truth? Yes, I dare. /No, I darent.1.How dare you accuse me of lying!2.He darent admit this.1.Only a few journalists dared to cover the story.2.He doesnt dare (to) go there alone.3.Dont you dare (to) touch it?用于

34、表示“需要，必要”之意。做情态动词时，仅用于否定句和疑问句，只有现在时，过去式要用neednt have，疑问式用need+人称?,否定式用need not(即neednt），做实义动词时，其变化与一般的实义动词相同，后接带to的不定式（need doing = need to be done ）, 疑问式，否定式要在前面加do的相应形式用于表示“敢于”之意。做情态动词，没有人称和数的变化，主要用于否定句、疑问句和条件状语从句中用作实义动词时，其变化与一般的实义动词相同。在肯定句中，dare后接带to的不定式；否定句中，dare后既可接带to的不定式，也可接不带to的不定式。七七ought的用

35、法：的用法：情态动词情态动词用法用法例句例句ought to do1.You ought to take care of him.2.Ought I to go now?Yes, you ought to. /No, you oughtnt to.1.He must be home by now. (断定他已到家)2.He ought to be home by now. (不十分肯定)3.This is where the oil must be. (比较直率)4.This is where the oil ought to be. (比较含蓄)说明：说明：should与与ought to

36、表示表示“应该应该”时的区别时的区别You_ help them with their work. You are his father. You _get him to receive good education.表示“应该”之意表示推测。注意与must表示推测是的区别 should ought toshould 表示自己的主观看法，而ought to的语气中，含有“按道理应该”之意。若要反映客观情况或涉及法律义务和规定，一般用ought to。Shall I go and buy more fruit for the party? No, I have already bought 3

37、baskets. That _ be enough.A. can B. ought to C. may D. mightHe used to teach in that university and I _ ride past it on my way to work.A. would B. could C. should D. mightWould you be here to attend the English party this evening? Yes, we _. A. shall B. would C. will D. must八八“情态动词情态动词+have done”用法用

38、法情态动词情态动词+have done用法用法例句例句must have done 1.She must have gone through a lot.2.He must have visited the White House during his stay in the United States.may/might have done1.You may have learnt the news.2.He may not have heard his name called.3.Sorry Im late. I might have turned off the alarm clock

39、and gone back to sleep again.canhave donecannot have done1.Where can she have gone?2.Could he have done such a foolish thing?3.The boy cant have finished reading the book so sooncould have done1.He could have killed himself driving at a dangerous speed.2.You could have done better, but you were too

40、careless.might have done1.You should not swim in that sea. You might have been eaten by a shark.2.He might have given him more help, thought he was busy.表示对过去已经发生的行为进行表示对过去已经发生的行为进行肯定肯定推测，意为推测，意为“想必，准是，想必，准是，一定做了某事一定做了某事”只用于只用于肯定句肯定句表示对过去已发生行为的表示对过去已发生行为的可能可能推测，意推测，意为为“也许也许/或许已经（没有）或许已经（没有）“。一。一般用于肯

41、定句或否定句中，不用于疑问般用于肯定句或否定句中，不用于疑问句。用句。用might则表示语气更加不肯定。则表示语气更加不肯定。表示对过去发生的行为的怀疑和不肯定，表示对过去发生的行为的怀疑和不肯定，通常用在否定句和疑问句中。（通常用在否定句和疑问句中。（can换成换成could时语气委婉）时语气委婉）可用于肯定句中，表示可用于肯定句中，表示“可能已可能已经经”之意，此外，还可以表示过之意，此外，还可以表示过去能做而没做的事，有一种对过去为去能做而没做的事，有一种对过去为付诸实施的事情的惋惜。付诸实施的事情的惋惜。表示表示“本来可能本来可能，但实际上没有发，但实际上没有发生的事情生的事情”。另外

42、，还可以表示。另外，还可以表示“本来本来应该或可以做某事应该或可以做某事”之意，含有轻微的之意，含有轻微的责备语气。责备语气。should/ought to have done1.He should have known that the police would never allow this sort of thing.2.You ought not to have refused his offer.neednt have done1.You neednt have watered the plants, for it is going to rain.had better have

43、done1.You had better have started earlier.2.You had better not have scolded her.would rather have done1I would rather have taken his advice.2I would rather not have told him the truth.用于肯定句时，表示本该做某事，用于肯定句时，表示本该做某事，而实际上未做；用于否定句时，而实际上未做；用于否定句时，则表示不该做的事反而做了。则表示不该做的事反而做了。表示做了本来不必去做的事。表示做了本来不必去做的事。用于事后的建

44、议，含轻微责备的用于事后的建议，含轻微责备的口吻，意为口吻，意为“当时最好做了某当时最好做了某事事”，其否定式，其否定式had better not have done表示相反的含义。表示相反的含义。表示表示“当时宁愿做了某事当时宁愿做了某事”，其否定式其否定式would rather not have done表示相反的含义，表示相反的含义，两者都表示两者都表示“后悔后悔”之意。之意。1The thief _ in from the kitchen window as the door was closed. A. may climb B. must have climbed C. coul

45、d have climbedD. should have climbed2I 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 receiveD. ought to have receive3.There were already five people in the car, but they managed to take me as well. It _ a comfo

46、rtable journey. A. cant B. shouldnt be C. must have been D. couldnt have been1.-There were already five people in the car but they managed to take me as well. -It _a comfortable journey. ( ) A. cant be B. mustnt have been C. shouldnt be D. couldnt have beenD2.The fire spread through the hotel very q

47、uickly but everyone _ get out. ( ) A. had to B. would C. could D. was able toD3. Peter _ come with us tonight, but he isnt very sure. A.must B. can C. may D. willC4. - Could I call you by your first name? - Yes, you_. A. will B. could C. may D. mightC5. Sorry, I m late. I _ have turned off the alarm

48、 clock and gone back to sleep again. A.might B. should C. can D. willA6.-Excuse me, but I want to use your computer to type a report.-You _ have my computer if you dont take care of it.A. shant B. might not C. neednt D. shouldntA7. -When can I come for the photos ? I need them tomorrow afternoon. -T

49、hey _be ready by 12 : 00 . A. can B. should C. might D. needB8. With so much work on hand, you _to see the game last night. A. mustnt go B. could have goneC. shouldnt go D. shouldnt have goneD9.Johnny, you _play with the knife, you _hurt yourself. ( )A. wont ; cant B. mustnt ; mayC. shouldnt ; must D. cant ; wouldntB10. I missed the bus, so I _ go home on foot. A. must B. may C. can D. had toD