1、1.can-could表示能力,可能性表示许可、请求,常译为“可以”表示说话人的猜测，用来表达惊异、怀疑、不相信等态度，主要用于疑问句和否定句I can speak English.He could write music when he was four.与过去有关的能力更客气、委婉惊异怀疑不可能、不相信Can I use your dictionary?Could I see your passport?I believe her.She cant be such a girl.What can the children be doing?The ground isnt wet.It ca
2、nt have rained last night.注意can与be able to的区别a.can常指现在,be able to 用于多种时态。They will be able to tell you the news soon.b.过去式含义不同：was/were able to 设法做成某事 (managed to do sth./succeeded in doing sth.)could仅表示有可能、能够做某事,事实上不一定去做。Most people were able to escape from the burning building.Im afraid I couldnt
3、arrive on time.2.must 表示“必须，应该”否定回答时常用neednt或dont have to.Must I go there in person?我必须亲自去吗？We must always follow the Party.我们要永远跟着党走。表示“必然”All men must die.人总是要死的。表示推测，“准是”、“一定”，否定形式为cantShe must be at home now.她现在准在家。He must have told you that yesterday.昨天他一定已经告诉你了注意must与have to的区别1.have to表示由于客观因
4、素不得不做must表示说话人的主观意志,看法e.g.We must hand in our papers today.今天我们必须把卷子交上去。（主观看法）e.g.We have to get there before dark.天黑前我们必须到达那里。（客观需要）2.have to2.have to有人称、数、时态的变化，而有人称、数、时态的变化，而mustmust只有一种形式。只有一种形式。e.g.He had to look after his sister yesterday.3.3.否定结构中否定结构中 dont have todont have to表示表示“不必不必”mustnt
5、mustnt表示表示“禁止禁止”。e.g.You dont have to tell him about it.你没必要把此事告诉他。e.g.You mustnt tell him about it.你一定不要把这件事告诉他。3.may-might 许可，可以e.g.You may borrow the back numbers.你可以借过期期刊。May I come in?Might I go to the hospital to see my father?否定形式为may not,但表示“不可以”或“禁止”时用must not(mustnt).e.g.ay I watch TV now?
6、我现在可以看电视吗？o,you mustnt.不，你不可以看。may,might还可以表示推测,但might可能性比may 小。e.g.There may be a few copies left in the bookstore.书店里可能还有几本书。They might have been killed by radiation.may 放在句首,表示祝愿。e.g.May God bless you!征询对方许可更委婉或许，很不确定Peter _come with us tonight,butPeter _come with us tonight,buthe isnt very sure
7、yet.he isnt very sure yet.A.must A.mustB.mayB.may C.can C.canD.willD.will答案答案BB.表可能性只能用表可能性只能用maymay。此句意可从后半句推出。此句意可从后半句推出。should 应该；ought to义务，责任，语气稍重一些。e.g.You should keep your promise.你应该遵守你的诺言。We ought to help them when they are in trouble.当他们有麻烦时，我们有责任帮助他们。should should 和和ought to ought to 都为都为
8、“应该应该”的意思，可用于各种人称。的意思，可用于各种人称。4.should 和 ought toought to 着重表示客观要求,含有法律上或道义上的责任。should 往往表示说话者的主观意见,表示一种必要性。Ought he to go?Ought he to go?Yes.I think he ought to.Yes.I think he ought to.Lets do some exercisesin our books on Pages44!表示否定的情态动词的用法表示否定的情态动词的用法:mustnt mustnt 不准；禁止不准；禁止neednt neednt 没必要没必
9、要(=dont have to)(=dont have to)cant cant 不能；不可能不能；不可能may not may not 不可以；可能不不可以；可能不shouldnt shouldnt 不应该不应该(=ought not to)(=ought not to)情态动词表推测情态动词表推测1.1.情态动词情态动词+v.v./bebe 对现在或将来的对现在或将来的推测推测I dont know where she is,she mayI dont know where she is,she maybe in Wuhan.be in Wuhan.2.2.情态动词情态动词+be+be+v
10、-ingv-ing 对现在或将对现在或将来正在进行的情况进行推测来正在进行的情况进行推测At this moment,our teacher mustAt this moment,our teacher mustbe correcting our exam papers.be correcting our exam papers.3.3.情态动词情态动词+have+have+vv-ed-ed对过去情况对过去情况的推测。的推测。Philip may(might/can/could)have Philip may(might/can/could)have been hurt seriously i
11、n the car accident.been hurt seriously in the car accident.4.4.情态动词情态动词+have been+have been+vv-ing-ing对过去对过去正在发生事情的推测。正在发生事情的推测。Your mother must have been looking Your mother must have been looking for you.for you.He is at home.(事实)He must be at home.（非常肯定的推断）He could be at home.（很可能）He ought to be
12、at home.（很可能）He may be at home.（仅仅可能而已）He might be at home.（或许,非常不确定）情态动词表推测时的不同的“肯定”程度：He might not be at home.（也许不在家）He may not be at home.（比might可能）He couldnt be at home.（很可能不在家）He cant be at home.（一定不在家）He isnt at home.（事实）1.Could I borrow your dictionary?Yes,of course,you_.A.mightB.will C.canD.
13、should 答案答案CC couldcould表示委婉的语气，并不为表示委婉的语气，并不为时态。答语中时态。答语中of courseof course，表示肯定的，表示肯定的语气，允许某人做某事时，用语气，允许某人做某事时，用cancan和和maymay来表达，不能用来表达，不能用couldcould或或mightmight。2.Shall I tell John about it?No,you _.Ive told him already.A.needntB.wouldnt C.mustntD.shouldnt答案答案AA needntneednt 不必，不用。不必，不用。wouldntw
14、ouldnt 将不将不,不会的。不会的。mustntmustnt禁止、不能。禁止、不能。shouldntshouldnt 不应该。不应该。本题为不需要，不必的意思，应用本题为不需要，不必的意思，应用needntneednt。3.Dont forget to come to my birthday party tomorrow._.A.I dontB.I wont C.I cantD.I havent 答案答案BB willwill既可当作情态动词，表请既可当作情态动词，表请求、建议、也可作为实义动词表求、建议、也可作为实义动词表“意愿、意志、决心意愿、意志、决心”，本题表示决，本题表示决心，选
15、心，选BB。4.Tom ought not to _ me your secret,but he meant no harm.A.have toldB.tell C.be tellingD.having told答案答案AA 由于后句为过去时，告诉秘密的由于后句为过去时，告诉秘密的动作又发生在其前因，此地应用过去完动作又发生在其前因，此地应用过去完成时，但它在情态动词成时，但它在情态动词ought toought to 后，所后，所以用以用havehave。1.We _ have proved great adventures,but we have done the greatest mar
16、ch ever made in the past ten years.(2016 天津)A.neednt B.may not C.shouldnt D.mustnt2.Black holes _ not be seen directly,so determining the number of them is a tough task.(2013 上海)A.can B.should C.must D.need3.Some aspects of a pilots job _ be boring,and pilots often _ work at inconvenient hours.(2015
17、 湖南)A.can;have to B.may;can C.have to;may D.ought to;must4.As you worked late yesterday,you _ have come this morning.(2016 陕西)A.maynt B.cant C.mustnt D.neednt5.She looks very happy.She _ have passed the exam.I guess so.Its not difficult after all.(2013 江苏)A.should B.could C.must D.might6.一What does
18、the sign over there read?一“No person _ smoke or carry a lighted cigarette,cigar orpipe in this area”(2014 四川)A.will B.may C.shall D.must7.Turn off the TV,Jack._ your homework now?Mum,just ten more minutes,please.(2017 辽宁)A.Should you be doing B.Shouldnt you be doing C.Couldnt you be doing D.Will you be doing
