情态动词ppt课件.ppt

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1、情态动词用法归类,只作情态动词的 can/could,may/might,ought to,must可情态可实义的 need,dare 可情态可助动词的 shall/should,will/would相当于情态动词的 have to,used to,表示推测的情态动词表达“情感、态度、语气”等方面的情态动词情态动词+have done,（一）表示推测的情态动词,对现在或将来情况推测，用情态动词+do/be/be doing；对过去的推测，用情态动词+have done/been；,表示肯定推测的情态动词按可能性大小依次为 mustshould/ought tomaymightcould；否定推

2、测，常用cant/couldnt，译为“根本不可能”、“想必不会”，表示推测的语气非常肯定，may not/might not译为“可能不”、“也许不”，表示推测的语气不很肯定。,must表示对某人某事的猜测,作“准是”,“一定”,一般用于肯定句中。Youmustbethenewteacher.Hemustbejoking.,should(not)/ought(not)to表示根据常规或常识推测，表示“某事应该或不应该发生”，语气比must或cant/couldnt稍弱。e.g.Hows your tour around the West Lake?Is it beautiful?It _ b

3、e,but it is now heavily polluted.A.will B.would C.should D.must【答案】C,can,could表达推测时，一般用于疑问句和否定句中；e.g.Can the news be true?He cant be in the classroom now,for the light is out.can用于肯定句中表示一种理论上的可能性，并不牵涉是否真的会发生；The road can be blocked.could用于肯定句中，语气比can更弱。,(4)may(not)/might(not)表达一种不太把握的推测，意为“或许，可能”；mi

4、ght的语气比may较婉转.May表示说话人的猜测:“也许”“可能”:通常只用于肯定句和否定句中。e.g.-I believe the man is from England.-But I may be wrong.The guest may arrive this afternoon.,might表示现在的可能，其可能性要比may 小。如：e.g.She might go home tomorrow.说不定他明天会回家。,（二）表达“情感、态度、语气”等方面的情态动词1.must表达“情感、态度、语气”主要有以下用法：(1)表示主观的义务和必要，主要用于肯定句和疑问句，意思为“必须，得，要”

5、；由must引起的疑问句，肯定回答要用must或have to，否定回答要用neednt或dont have to,意思是“不必”。,MustIfinishallassignmentsatatime?,Yes,you must.No,youneednt.,表示“必须”这个意思时，must和haveto稍有区别。must着重说明主观看法，haveto强调客观需要。,must和 haveto,I dont like this TV set.We must buy a new one.There was no more bus.They had to walk home.,(2)must的否定形式m

6、ustnt表示禁止，意思是“不能，不许”。例如：(2008上海春)When I was young,I was told that I _ play with matches A.wouldnt B.neednt C.mustnt D.darent【答案】C,must还可以用来表示责备、抱怨的感情色彩，意思为“偏要，硬要、干嘛”。例如：He must come and worry her with question,just when she was busy cooking the dinner.,2.should“应该”，表示“责任和义务”。例如：You should keep your

7、promise.你应该遵守诺言。,3.shall(1)shall用于第一和第三人称，常用于疑问句中，用来征求对方意见。例如：Shall we go by train,Mom?Shall they wait here or outside?(2)用于第二和第三人称，表示“命令、威胁、警告、允诺、”等。例如：You shall fail if you dont work harder.He shall have the book when I finish reading.,(3)shall也用于宣布法律、规定的要求。例如：What does the sign over there read?“N

8、o person _ smoke in this area.”A.will B.may C.shall D.must【答案】C,4.can(1)can可以用来表示惊异、怀疑、不相信的态度，主要用于否定句、疑问句或感叹句中。(NMET2003全国)How _ you say that you really understand the whole story if you have only covered only part of the article?A.can B.must C.need D.may【答案】A(2)can也可以用来表示请求或许可。Can I sit here?,(3)ca

9、n可以表达一般的或永久的能力。be able to也可表达能力，但常用来表达在某件事情中所表现出来的能力，尤指克服困难能够完成某事。例如：(NMET2006福建)If it were not for the fact that she _ sing,I would invite her to the party.A.couldnt B.shouldnt C.cant D.might not(NMET1997)The fire spread through the hotel very quickly but everyone _ get out.A.had to B.would C.could

10、 D.was able to【答案】C D,5.would(1)will与would可表示“意愿；意志”。(NMET2008北京)John promised his doctor he _ not smoke and he has never smoked ever since.A.might B.should C.could D.would【答案】D,(2)would表示过去倾向性或习惯性的动作。used to 也有这一用法，但used to即可用来表达过去的习惯性的动作，也可用来表示过去的状态。例如：(NMET1996上海)When he was there,he _ go to that

11、 coffee shop at the corner after work every day.A.would B.should C.had better D.might(NMET2007安徽)In my opinion,life in the twenty-first century is much easier than _.A.that used to be B.it is used to C.it was used to D.it used to be【答案】A D,（三）情态动词+have done,must表示对某人某事的猜测;对过去发生的事情作肯定判断用must have don

12、e Thereisnobodyhere.Theymusthaveall gonehome.,can和could接动词的完成形式。could have done:表示本可能做某事却没做。(有惋惜、遗憾或委婉批评之意，也可以表示对过去动作的推测)e.g.a.You could have done better,but you didnt try your best.b.This glass iscracked.Someone could have dropped it cant/couldnt have done:用于否定句时表否定推断，推测肯定没做；用于疑问句时意为“难道真的做了吗”，表示怀疑。

13、e.g.They cant have gone out because the light is still on.Can he have done such a foolish thing?cant have done 的语气比 couldnt have done 要强一些,“should+have+过去分词”表示本应该在过去做但没有做。should(not)/ought(not)to have done本（不）应该做某事，但却没有做或做了，含有责备或后悔之意（NMET2008江苏）Im sorry.I _at you the other day.Forget it.I was a bit

14、out of control myself.A.shouldnt shout B.shouldnt have shouted C.mustnt shout D.mustnt have shouted【答案】B,neednt have done本没有必要做某事但却做了。要注意neednt do则表达“没有必要去做某事”，时间上应该是现在或将来。例如：(NMET2005福建)Catherine,I have cleaned the room for you.Thanks.You _ it.I could manage it myself.A.neednt do B.neednt have done

15、 C.mustnt do D.shouldnt have done【答案】B,would(not)have done本来(不)会发生某事，但却（发生了）或没有发生。常用于虚拟条件句或含蓄虚拟条件引导的虚拟语气，表示对过去所发生事情结果的假设。I would have told you all about the boys story,but you didnt ask me.我本来会告诉你这个小男孩的故事，但是你没有问我。Without your help,I wouldnt have achieved so much.没有你的帮助，我是不会取得如此大的成绩。,might have done表示“本来可能”，但实际上没有发生的事。例如：(NMET2008江西)What a pity!Considering his ability and experience,he _ better.A.need have done B.must have doneC.can have done D.might have done【答案】D,