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1、情态动词,the modal verb,一、情态动词的特点:1.没有人称和数的变化。2.有些情态动词有过去式的变化:e.g.willwould,cancould,maymight,daredared,本身有一定的词义，但不能独立做谓语，它和实义动词一起构成合成谓语。常用情态动词can/could;may/might must should/ought to shall will dare need补充短语：can never/cant.too 无论怎样也不过分。越。越好you cant be too careful while cross the road.,情态动词,1 Can 表示与生俱来
2、的一种能力 be able to 强调通过后天学习和努力获得的能力或在某个客观的场合和背景下能做到的。He can swim,and he will be able to swim ashore when the boat sinks.2 表示一种许可 其中could 比can更委婉、更礼貌。Could I take this seat,please?can I use your pen?Yes,you can.,3 表示可能性 he cant have gone to shanghai,because I saw him just now.Could have done 本该做而未做（与过去
3、事实相反的假设）he could have gone there by bus.4 表 不肯定 can this be true?It cant be true.Do you think he could have remembered the details under those circumstances?,can/could 的用法,1、用于正式场合表示许可May I use your dictionary,professor smith?yes,you may.2、用于肯定句，疑问句，否定句中表示可能性Youd better take an umbrella with you;it
4、may rain.if he had follow my advice,he might have passed the driving test.,May/might 的用法,3、用于感叹句中表示愿望 may you have a good luck.4、用于目的状语从句中表示“目的”We started early in the morning so that we might arrive there in time for the meeting.5、表示让步 Any state should provide its people with the right to exist no
5、matter what political system it may adopt.,1、表示即刻或将来的责任或义务 You must clean the classroom after school.对must 的提问 回答要用neednt注意：must指自己的主观的责任或义务，have to 指外界施加的责任或义务I must study harder.I have to stay at home looking after my mother because she is ill.,Must 的用法：,2、must 用于否定句中表禁止 you mustnt play football i
6、n the street.3、用于肯定句中表示“确定或可能”you must be a student.I must look funny in this hat.4、表示很有把握的推断:一定,准是。haveto,1).表示必须要做的事:必须3)-MustIgettothestationbeforethreeoclock?Yes,youmust.(No,youneednt.)4)Imafraidyouwillhavetowaitawhile.6)Mary_ beinParis,Isawherintownonlyafewminutesago.A.mustntB.shouldntC.cantD.m
7、aynot,3.must,C,1、should加动词原形 表示责任、义务、建议；we should do our work well.2、虚拟语气中 should可以省略。Should 用在虚拟语气中表示“惊讶、失望、目的”Its strange that you should say that to your mother.,Should的用法：,3、should have done 过去该做而没有做的事，含有委婉的责备eg:you should have told me that news earlier.Should+have done 针对过去某事的推测he started so ea
8、rly,so he should have arrived by now,1、表道德义务或建议 you ought to go there at once.2、ought to have done 对过去某事的推测或责备 you ought to have studied harder.注意：ought to 的语气比should 强,ought to 的用法：,1)You tosmoketoomuch.2)She_forwhatshehasdone.A.oughttopraise B.oughtbepraisedC.oughttohavepraised D.oughttobepraised,
9、oughtnt,1)Dontsmokeinthemeetingroom,_you?A.doyou B.willyou C.canyou D.couldyou 2)Itsmybirthdaytomorrow.Dontforgettocometomyparty.-_.A.IdontB.IwontC.IcantD.Ihavent,You have my dictionary as soon as Mary return it to.A.will B.shall C.would D.shouldHe can swim,and he survive when the boat sinks.A.can B
10、.is able to C.may D.could,B,B,I clean the classroom?No,you My mother is ill in bed,and I stay at home and look after her.He take a nap after lunch and have a walk after supper I use your pen?Yes,of course.Mary is very timid.She go out at night.The ground is wet.It have rained last night.Since you ar
11、e his elder brother,you take care good of him.,must,neednt,have to,would/will,can/may,must,should/must,1.beableto表示经过努力后,能够做到;2.can1).表示体力或脑力方面的能力;2).表示允许、可能性。could是can的过去式,表示过去有能力及过去存在的可能性;用于疑问句表示委婉地提出问题。,can,beableto,1)Thefirespreadthroughthehotelveryquicklybuteveryone_getout.A.hadto B.would C.could D.wasableto 2)-Willyoustayforlunch?-Sorry,_.Mybrotheriscomingtoseeme.(NMET99)A.Imustnt B.Icant C.Ineednt D.Iwont,thanks for listenning,
