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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,情态动词,情态动词是一种本身有一定的词义，但要与动词原形及其,被动语态,一起使用，给谓语动词增添情态色彩，表示说话人对有关行为或事物的态度和看法，认为其可能、应该或必要等。情态动词后面加动词原形。,什么是情态动词？,情态动词的语法特征,1.,情态动词有一定的意义，只表示,期待,或,估计,某事的发生，不能表示正在发生或已经发生的事情。,2.,没有人称和数的变化,，即情态动词第三人称单数不加,-s,。,3.,不能独立使用,，它和后面的动词构成谓语。,4.,情态动词,除,ought,和,have,外,，后面只能接动词原形。,5.,情态动词,没有非谓语形式,，即没有不定式、分词等形式。,常见情态动词：,can/could,may/might,ought to,must,need,dare,shall/should,will/would,have to,used to,表示能力,表示可能性,表请求或允许,can,和,could,：,1)can,的主要用法：,A._,：,eg,.The girl,can,dance very well.,B._,：,eg,.,Can,the news be true?,C._:,eg,.,Can,I sit here?,2)could,的主要用法：,A.could,是,can,的过去式,表示过去的能力和推测,eg,.,她不可能在说谎。,She couldnt be telling lies.,B.could,可代替,can,表示请求,语气比,can,更委婉,eg,.,Could,you lend me your dictionary,？,Could,I use your bike?,3),can/could have done,“,本可以、本可能做某事”用于肯定句中，表示对,过去发生,的事情作出的判断。,你本来可以考得更好。,You could have had a better mark.,4),can/could not have done,对,过去发生,的行为进行推测,:,不可能做了某事,刚才我还看见他了，所以他不可能出国了。,I saw him just now so he couldnt have gone abroad.,门是锁着的，所以她不可能在家。,The door was locked,，,so she couldnt have been at home.,may,和,might,1.may,的主要用法：,A._,eg,.,May,I come in?(,请求,),You,may,go now.(,允许,),B._,eg,.,I believe the man is from England.,But you,may,be wrong.,may/might,表示推测时，只能用于陈述句，表示对现在或将来要发生的动作把握不大。,表示请求、允许,;,比,can,正式,:,表示猜测：,The road,may,be blocked.,这条路可能不通了。,在疑问句中，表示可能性用,can,。,例如：,Where,can,he be?,他会在哪呢？,可能性从大到小,:mustcan could may might,表示祝愿,;,语气较正式,:,C._,eg,.,May,you succeed!,May,you have a good journey!,2.might,的用法,:,多在间接引语中表示,过去的可能和允许,。,She said that he,might,take her bike.,她说他可以拿她的自行车去用。,3.might/may have done,表示对过去发生的动作进行表示可能性的推测。,他可能去医务室了。,He may have gone to the clinic.,他可能已经从报纸上知道这个消息了。,He might have read about the news in the newspaper.,（助动词）,（情态动词）,will,和,would,：,1.,_,用于构成将来时是助动词。,用于表“,意志,/,决心,/,请求,”时是情态动词。,would,亦同理。,I,will,tell you something important.,我将要告诉你一些重要的事。,Will,you tell her that Im here?,请您告诉她说我在这儿，好吗,?,will,是助动词或是情态动词。,2._,If you want help,let me know,will,you?,如果你需要帮助,让我知道,好吗,?,Will,you type this,please?,请打印这个，好吗？,Wont,you sit down?,请坐下，好吗？,will,在疑问句中用于第二人称,表提出请求。,（表请求）,（表意愿）,（表许可）,3._,Would,you help us,please?,请您帮助我们，好吗？,Id,go there with you.,我要和你一块到那儿去。,Teacher,wouldnt,allow it.,老师不会允许这件事。,would,比,will,语气委婉。,shall,should,和,ought to,1.,在陈述句中,shall,用于第二、三人称，表示允诺、警告、命令、决心等。,You,shall,do as I say.(,命令,),Nothing,shall,stop me doing it.(,决心,),Tell him that he,shall,have the book tomorrow.(,允诺,),2.,在疑问句中,用于第一、三人称，表示请求或征求意见。,Shall,I open the window for you,？（征求意见）,Shall,he fetch some water for you,？（请求）,shall,用于,构成将来时是助动词,用于表示允诺、警告、命令、决心和请求或征求意见时,是情态动词,3.should,常表示劝告、建议、命令，与,ought to,意义相近，但,ought to,多表示责任、义务，语气强烈。,Young people,should,learn how to use computers.,Every citizen,ought to,obey law.,You,ought not to,go.,4.should/ought to have done,表示责备或批评,意为“本应该,但”,ought to,的语气更强烈,用于否定则表示“本不该,但”。,You,should/ought to have told,her the truth earlier.,She,shouldnt have left,without saying a word.,5.Should,用于表示可能性的推测时,表“应该，很可能”。,They left at 5:30.They,should,get there now.,表示必然性。,表示强制,/,义务。,must,must,的主要用法：,1._,eg,:We,must,all die.,人总要死的。,2._,eg,:You,must,get up early.,你必须早起来。,例如：,We,mustnt,waste our time.,May I take this magazine out?,No,you,mustnt,.,注意,:must not “,禁止”。,must,用于一般疑问句的时候，肯定回答用,yes,please,等，其否定回答用,neednt,或者,dont have to,。,must,表示推测时，只能用于,肯定句,。,must do,对,一般时,的,肯定,推测,must be doing,对,现在的动作,进行肯定推测,must have done,对,过去发生的事情,作出的肯定判断,他们买了一辆新车。他们一定很有钱。,They have bought a new car.They,must have,a lot of money.,他现在一定在看小说,.,He,must be reading,novels now.,路是湿的。昨天晚上一定下雨了。,The road is wet.It,must have rained,last night.,need,1.,作情态动词时,仅用于否定或疑问句,后接动词原形,表“需要”。,You,neednt,return the book now.,Need,he start from the beginning?,Yes,he must./No,he,neednt/doesnt,have to.,2.neednt have done,表示做了本不必要做的事情,意为“,本不必要,”,。,Our color TV set is still good enough.You,neednt have bought,a new one.,3.need,作实义动词时,表示“需要”，有人称、时态和数的变化。,He,needs,to finish it this evening.,The classroom,needs,cleaning.,可兼作实义动词的情态动词：,need,，,dare,1.,作为情态动词用，常用在否定句和疑问句中。,Dare(Need)+S,(,主语,),+V,(,动词原形,),S+darent(neednt)+V,I darent walk through the forest at night.,Dare you walk through the forest at night?,You neednt return the book now.,Need he go yesterday?,2.,作实义动词用，常用在肯定句中,有人称、时态和数的变化。,He needs to go there himself.,He has grown up,we dont need to worry about him.,3.sth.(sb.)need(want,request)+doing/to be done.,The house needs cleaning/to be cleaned.,The boy needs sending to the hospital at once.,The plants want watering every day.=The plants want to be watered every day.,句型 时 态 动 词,情态动词,dare,实义动词,dare,肯定句,现在时,dare do dare/dares to do,过去时,dared do dared to do,否定句,现在时,darent/dare not do do/does not dare(to)do,过去时,dared not do did not dare(to)do,疑问句,现在时,Dare he do?Do you/Does he dare(to)do?,过去时,Dared he do?Did he dare(to)do,【,高考链接,】,1.(2012,全国卷,)Im going to Europe on vacation together with John if I _ find the money.,A.can B.might C.would D.need,【,解析,】,选,A,。考查情态动词。句意,:,如果我能弄到钱,我会与约翰一起去欧洲度假。从主句的时态形式来看,该句不是虚拟语气,而是真实条件,所以用,can,表示“能够”,相当于,be able to;might,表示更小的可能性,;would,表示意愿,;need,必要。,2.(2012,全国卷,)I_ use a clock to wak
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