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Unit 2 Modal verbsHe can type 100 words within one minute.abilityYou must work hard to win the gold medal.necessityShe might get a ticket for the concert.possibilityYou may come in and sit down.permissionLook at following sentences,pay attention to the words in red.Modal verbs情态动词情态动词除了可以表示除了可以表示能力、必要、可能能力、必要、可能、允许允许外，还可表达外，还可表达愿望愿望、猜测猜测等意等意:Example:I will be a famous singer in the future.(wish)He must be at home now.(guess)Can you help me with my training?(request)Shall we do some exercise this morning?(suggestion)情态动词情态动词不能独立作谓语，其后必加不能独立作谓语，其后必加动词动词原形原形，共同构成复合谓语；，共同构成复合谓语；Children should respect their parents.情态动词情态动词没有没有人称人称和和数数的变化；的变化；I/You/She/We can speak English.常见的情态动词有：常见的情态动词有：can,could,may,might,will,would,must,have to,had better,shall,should,ought to,need,dare can&could1)表能力表能力 can 意味着凭体力或脑力或技术等可以意味着凭体力或脑力或技术等可以 现在的能力和将来的能力现在的能力和将来的能力 意为：能够意为：能够 can can 能够能够 cant cant 不能够不能够 could 表过去的能力表过去的能力（常用于间接引语）（常用于间接引语）I can speak Spanish.Fire cant destroy gold.I could swim when I was only six.Father said I could swim in the river.2)表可能性表可能性 意为：可能，意为：可能，can/could 表示客观上的/理论上的可能性，并不牵涉真的会发生，多用于肯定句中 Anyone can make mistakes.can/could 表示主观上的可能性，即说话者的主观推测,多用于否定句或疑问句中 That cant be Mary-Shes in hospital.You cant be hungry-you had lunch only one hour ago.3)3)表示允许表示允许,请求请求（和（和may意思相近）常见于口语。意思相近）常见于口语。多用于否定和疑问句中多用于否定和疑问句中 Can(May)I come in?You cant smoke in the classroom.表示请求，口语中常用could代替can,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。Could you lend me some money?你能借给我一些钱吗？4）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 the news be true?这消息真的吗？How can you be so foolish!你怎么这么傻！can/could have done 表示对过去某种情况的怀疑或不确定 一般用于否定句和疑问句中 cant/couldnt have done 表对过去的否定性推测，意为“不可能”Could have done 表示本来能做某事而实际上没有做 He cannot have been to that town.I could have climbed that mountain.may&might 1)1)表示请求、可以、允许表示请求、可以、允许 You may watch TV now.2)2)当回答由当回答由may引起的问题时引起的问题时,否定否定答语要用答语要用 must not,表示表示“不不许可许可”、“不应该不应该”、“不行不行”。May I come in?(=can)Yes,you may.No,you mustnt.3)3)表建议表建议（may/mightmay/might和和as well连用）连用）表示表示“还是还是的好的好”You may as well stay where you are.Its too late.You might as well not go.4)表祝愿（用于祈使句中）May you have a good time in New York.might 1)在间接引语中表过去的在间接引语中表过去的“可能可能”和和“允许允许”She said that he might take her dictionary.除在间接引语中外，除在间接引语中外，might一般不表示过去的一般不表示过去的“可能可能”与与“许可许可”。表过去的。表过去的“可能可能”可用可用could，表过去的，表过去的“许可许可”可用可用were(was)allowed to2)表现在的表现在的“可能可能”，其可能性要比其可能性要比may小。小。Electric irons could be dangerous;they mightgive you a severe shock.May not 指可能不 Can not 指不可能 He may come or may not come.Im not too sure about that.He cant believe your so-called excuses.may/might have done 表示对过去某种情况进行不肯定的推测主要用于肯定句和否定句中 You might have read about it in the papers.They may not have known it before hand.他们事先可能不知道这事儿。must&have to 1 1、must 的主要用法。的主要用法。1)1)表示必须、必要表示必须、必要(着重说话人的主观看法着重说话人的主观看法)We must do everything step by step.2)2)用用 must 提问时提问时,否定答复要用否定答复要用 neednt 或或 dont have to 表表“不必不必”、“无须无须”的意义。的意义。Must I go tomorrow?明天我必须去吗？明天我必须去吗？Yes,please.是的，请吧！是的，请吧！No,you neednt.(=dont have to)不，不必不，不必 must not 表示表示“不应该不应该”、“不许可不许可”、“禁止禁止”You must not smoke here.3）表示有把握的推测，只用于肯定句。）表示有把握的推测，只用于肯定句。It must be our headteacher.have to 的用法的用法have to 的含义与的含义与 must 是很接近的是很接近的,只是只是 have to比较强调比较强调客观需要客观需要，must 着重说明着重说明主观看法主观看法。I must clean the room.（主观想法）（主观想法）Its getting late.I have to leave now.（客观需要）（客观需要）另外，另外，have to 能用于更多时态：能用于更多时态：We had to be there at ten.We will have to reconsider the whole thing.have to 的否定式：的否定式：dont have to do“不必做不必做”。You dont have to go right now.Must have done 表示对过去发生事情作肯定性推测“过去一定做了什么”It must have rained last night,for the road is quite muddy.昨晚肯定是下雨了，因为路面很泥泞。否定形式 cant/couldnt have done过去不可能做了某事不能用mustnt have done He couldnt have gone abroad,for I met last night.他不可能出国了，因为昨晚我还见过他。Shall&should1、shall的用法的用法1)用于第一、三人称征求对方的意见，用于第一、三人称征求对方的意见，表示要不要表示要不要 如：如：What shall I wear on the journey?Shall he come at once?你要他马上来吗？你要他马上来吗？2)shall 用于第二、三人称时表说话人给对方的命令、警告、允诺、威胁用于第二、三人称时表说话人给对方的命令、警告、允诺、威胁 You shall have it back tomorrow.你你明天可以将它拿回。明天可以将它拿回。(允诺允诺)3）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，意为为“一定一定”。Students shall wear school uniforms in the school.学生在学校应该穿校服。学生在学校应该穿校服。*情态动词情态动词should,主要用法有：主要用法有：1)用于第一人称疑问句中询问对方的意愿，但语气用于第一人称疑问句中询问对方的意愿，但语气 较委婉温和，如：较委婉温和，如：What should we do now?我们现在该怎么办？我们现在该怎么办？2)表示应该、必须，常与表示应该、必须，常与must 换用。例如：换用。例如：We should(must)master a foreign language at least.3)用于虚拟语气用于虚拟语气:It is suggested that he(should)be sent there at once.It is strange that he should say so.Should 1）need&dare这两个词只能算这两个词只能算“半情态动词半情态动词”，它们作情态动词用时，它们作情态动词用时，一般用在否定句和疑问句中，如果用在肯定句中，多一般用在否定句和疑问句中，如果用在肯定句中，多数是实义动词，一般现在时单数第三人称就要加数是实义动词，一般现在时单数第三人称就要加s，并，并有时态变化，后接不定式时须带有时态变化，后接不定式时须带to,试比较：试比较：Need I explain once more?（情态）（情态）The question needs to be discussed.（实义）（实义）She dare not tell the truth to him.（情态情态）We should dare to think,to speak and to act.She dare not go out at night by herself.（情态）（情态）从推测角度分：从推测角度分：可可 能能(1-50%)might;may;could;can很可能很可能(6090%)should;ought to;would;will肯肯 定定(100%)must不不 可可 能能(0%)cant-Theres someone at the door.Didnt you hear the bell?-It _ be Jack.might/may/should/must/cant Pay attention to the differences:must have done should/ought to have done neednt have done1.91 A computer _ think for itself;it must be told what to do.A.cant B.couldnt C.may not D.might not 2.92-Shall we go skating or stay at home?-Which _ do yourself?A.do you rather B.would you rather C.will you rather D.should you rather3.92 Could I borrow your dictionary?Yes,of course you _.A.might B.could C.can D.should4.93 Peter _ come with us tonight,but he isnt very sure yet.A.must B.may C.can D.will5.94 Shall I tell John about it?No,you _.Ive told him already.A.neednt B.wouldnt C.mustnt D.shouldnt6.94-Dont forget to come to my birthday party tomorrow.-_.A.I dont B.I wont C.I cant D.I havent7.96 Johnny,you _ play with the knife,you _ hurt yourself.A.wont,cant B.mustnt,may C.shouldnt,must D.cant,shouldnt8.97 The fire spread through the hotel very quickly but everyone _ get out.A.had to B.would C.could D.was able to 9.98When can I come for the photos?I need them tomorrow afternoon.They _ be ready by 12:00.A.can B.should C.might D.need10.99Will you stay for lunch?Sorry,_.My brother is coming to see me.A.I mustnt B.I cant C.I neednt D.I wont11.00Are you coming to Jeffs party?Im not sure.I _ go to the concert instead.A.must B.would C.should D.might12.02-Is John coming by train?-He should,but he _ not.He likes driving his car.A.must B.can C.need D.may*I thought you _ like something to read,so I have brought you some books.a,may b,might c,could d,must*There are plenty of time,she _ a,mustnt hurried b,couldnt hurried c,must not hurry d,neednt have hurried*The plant is dead.I _ it more water.a,will give b,would have given c,must give d,should have given*Where is my pen?I _ it.a,might lose b,would have lost c,should have lost d,must have lost*You _ return the book now.you can keep it till next week if you like.a,cant b.mustnt c,neednt d,may not*It still early,you _ a,mustnt hurry b,wouldnt hurry c,may not hurry d,dont have to hurry*Please open the window,_?a,cant you b.arent you c,do you d.will you*We _for her because she never came.a,mustnt have waited b,shouldnt have waited c,mustnt waited d.neednt waited*-May I stop here?-No,you _.a,mustnt b,might not c,neednt d,wont*Its a fine day.Lets go fishing,_?a,wont you b,will you c,dont we d,shall we*I didnt see her in the meeting room this morning.She _ have spoken at the meeting.a,mustnt b,shouldnt c,neednt d,couldnt*“could I borrow your dictionary?”“Yes,of course you_”a,might b,will c,can d,should*-Please dont make a noise.-_.Ill be as quiet as a mouse.a.yes,I wont b.no,I wont c,no,I will d.yes,I will*The young men has made so much noise that he_ not have been allowed to attend the concert.a,could b,must c,would d,should*One ought _ for what one hasnt done.a,not to be punished b.to not be punished c,to not punished d.not be punished*If you really want yourself to be in good health,you must _ always _so much.a,not,be smoking b,not,have smoked c,not,to smoke d.be not,smoking*Since the road is wet this morning,_last night.a,it must rain b,it must be raining c,it must have rained d,it must have been rain*-will your brother stay home tonight?-Im not sure.He _ to the cinema tonight.a,must go b,can go c,may go d,may be going*She is already 2 hours late.What _ to her?a,can have happened b,may have happened c should have happened d,must happen*You must be a writer,_?a,mustnt you b,are you c,must you d.arent you*I got up early that morning,but I _so because I had no work to do.a,mustnt have done so b.didnt need to do c,neednt have done d,cant have done
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