unit2_healthy_eating__grammar情态动词.ppt

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1、Grammar情态动词Modalverbs情态动词情态动词表示推测表示推测不表示推测不表示推测cancouldmaymightshallshouldwillwouldmustneed(neednt)dare(darent)usedtooughttohavetoYoungpeople_learnhowtousecomputers.Everycitizen_obeythelaw.You_breakthelaw.should常表示劝告、建议，常表示劝告、建议，oughtto多表示责任、义务，语气强烈。多表示责任、义务，语气强烈。should&oughttoshouldoughttooughtnott

2、o多数情况下，多数情况下，oughtto可与可与should互换使用。互换使用。shouldhavedoneoughttohavedone表示表示“过去应该做而未做过去应该做而未做”Yououghttohavemadethedecisionyesterday.=Youshouldhavemadethedecisionyesterday.Ishouldnthavemadesuchafoolishmistake.注意注意must&havetomust用用于于一一般般问问句句中中,肯肯定定回回答答用用must否否定式用定式用neednt或或donthaveto.mustnt表示表示“禁止，不允许禁止

3、，不允许”e.g.MustIfinishallassignmentsatatime?Yes,youmust.No,youneednt.Youmustntgetoffwhilethecarisstillmoving.must have done 表示对过去已经发生的行为进行推测，意为“一定做了某事”。1.It must have rained last night,for the road was very muddy.昨晚 一定是下雨了，因为地上很泥泞。2.We must have learned 2,000 words by the end of last term.到上学期为止我们一定学了

4、有两千个单词 。3.He must have gone to Beijing.他一定已经去北京了。may/might+have done表示对过去已发生行为的推测，意为“可能做了”。一般只用于肯定句和否定句中，might比may更不肯定。1.Its too late.I think he may have gone to bed.太晚了，我想他可能已经睡觉了。2.He may/might not have finished the work.他可能没有完成工作。could have done表示“本来能够而没能”，具有婉转的批评和责备之意。1.I could have passed my ex

5、am easily,but I made too many stupid mistakes.我本来能够轻易通过考试，但我犯了太多不该 犯的错误。2.You could have told me earlier.你本该早点告诉我的。can/could+have done表示对过去的行为的怀疑和不肯定，通常用在否定句和疑问句中。1.Can they have won the basketball match?他们可能赢了篮球赛吗？2.It couldnt have been Mr.Green.He has gone to New York.那不可能是格林先生的，他已经去北京了。neednt hav

6、e done“没有必要做却做了1.She neednt have gone to the station yesterday.2.You neednt have bought it.3.You need have come to school earlier this morning.need have done“有必要做却没有做”should have done“应该做却没有做”shouldnt have done“不应该做却做了1.-I wonder why they are late?-They _ the train.A.cant have missed B.could missC.m

7、ust have missed D.might missC2.Oh,Im not feeling well in the stomach.I _ so much fried chicken just now.A.shouldnt eat B.shouldnt have eaten C.mustnt eat D.mustnt have eatenB3.-Has Mike started?He said he would join in the party.-He _.He is a man of keeping his word.A.could have left B.must have lef

8、tC.cant come D.wont be coming4.-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.should be D.couldnt have been BD5.-Didthetrainarriveintime?-No.It_twohoursago.A.musthavearrivedB.oughttohavearrivedC.mustarriveD.ou

9、ghttoarrive6.MustIdrivetohishouseandpickupthechildren?No,.A.youshouldntB.youmightnot C.youneednt D.youmustntBC7.You_suchalongcomposition.Theteacheronlyaskedfor300words.Youhavewritten600.A.mustnthavewrittenB.couldnthavewrittenC.neednthavewrittenD.donothavetowriteC8.Thereissomeoneknockingatthedoor._itbeTom?A.canB.mustC.shouldD.oughttoA