1、Grammar情态动词的语法特征情态动词的语法特征1）情态动词情态动词不能单独做谓语，除不能单独做谓语，除ought和和have外，后面只能接不带外，后面只能接不带to的的不定式。不定式。2）情态动词没有人称，数的变化，但有些情态动词没有人称，数的变化，但有些情态动词，如情态动词，如can、will也有一般式和过去也有一般式和过去式的变化。式的变化。3）情态动词的情态动词的“时态时态”形式并不是时间区形式并不是时间区别的主要标志，不少情况下，情态动词的现别的主要标志，不少情况下，情态动词的现在式形式和过去式形式都可用来表示现在时在式形式和过去式形式都可用来表示现在时间、过去时间和将来时间。间、
2、过去时间和将来时间。l1.canl1)表能力can表能力时意味着凭体力或脑力或技术等可以无甚阻力地去做某事。lI can climb this pole.He is only four,but he can read.lFire cant destroy gold.can 和和could：l2)表推测、可能性用于否定与疑问结构中lCan the news be true?It cant be true.lWhat can he possibly mean?他可能是什么意思?lcan 用在肯定句中表示理论上的可能性(一时的可能)。lA house in the center of London
3、can cost a lot of money.lAttending the ball can be very exciting.The road can be blocked.l3)表示请求或允许请求或允许(和may意思相近)常见于口语。lCan(May)I come in?我能进来吗?lCan I smoke here?我可以在这里抽烟吗?2)could的主要用法是：的主要用法是：A.could是是can的过去式的过去式,表示与过去表示与过去有关的能力和推测有关的能力和推测:eg.Weallknewthattheyoungmancouldntbeadoctor.B.could可以代替可以代
4、替can表示请求、表示请求、“允许”。可表示委婉客气的提出问题或陈述看法Couldyoulendmeyourdictionary?CouldIuseyourbike?Yes,you can.Im afraid I couldnt give you an answer today.Can 与与 be able to do 的区别的区别l时态时态：can 只有现在时和过去(could),be able to do 有多种时态。（在将来时将来时，完成完成时以及非谓语动词非谓语动词中应该用 be able to do.）e.g.So far,doctors have been able to do v
5、ery little to treat(治疗)this kind of disease(疾病).Can表示一贯的能力，be able to表示客观能力和通过努力可以达到的能力1.I cant swim.But I am sure I will be able to swim through more practicing.2.The fire spread through the hotel,but everyone was able to get out3.When the boat sank he was able to swim to the bankYou cant be too ca
6、refulShe couldnt but agree to my idea.The girl couldnt help crying.I cant thank you enough.The film couldnt be any worse.I burst out laughing;I couldnt help itCan或或could 的否定形式构成习惯短语的否定形式构成习惯短语Cant.too.Cant.enough.无论怎样。也不过无论怎样。也不过分。分。Cant(help)but do不得不做，只好做不得不做，只好做Cant help doing 情不自禁情不自禁Cant help i
7、t 没有办法没有办法Cant.+比较级比较级 再。不过了（表示最高级）再。不过了（表示最高级）may 和和might：may常用来表示：常用来表示：A.表示请求、允许表示请求、允许;比比can较为正式较为正式MayIcomein?Youmaygonow.(给予许可）给予许可）B.表示说话人的猜测表示说话人的猜测:“也许也许”“可可能能”:通常只用于肯定句和否定句中。通常只用于肯定句和否定句中。eg.-IbelievethemanisfromEngland.-ButImaybewrong.Theguestmayarrivethisafternoon.在疑问句中，表示可能性用在疑问句中，表示可能性
8、用can。如：如：Where can he be?他会在他会在哪呢？哪呢？C.表示祝愿表示祝愿;但语气较正式但语气较正式:eg.Mayyousucceed!Mayyouhaveagoodjourney!might的用法有的用法有:多在间接引语中表示过去的可能和允许。多在间接引语中表示过去的可能和允许。如如:Shesaidthathemighttakeherbike.她说他可以拿她的自行车去用她说他可以拿她的自行车去用表示现在的许可表示现在的许可,语气比语气比may较委婉较委婉,一般用于疑问句一般用于疑问句(包括间接疑问句包括间接疑问句),不可不可用于肯定句或者否定句。用于肯定句或者否定句。如如
9、:MightIhaveawordwithyou?我可以和你说句话吗？我可以和你说句话吗？lYou may well be rightlThere is nothing to do,so I may as well go to bed.lThe film is so boring,and we might as well not have come to see it.lMay well 很可能、有充分的理由可以很可能、有充分的理由可以lMay/might as well最好，不妨最好，不妨lMight as well have done 还不如还不如lMay.do/be.祝愿祝愿l 当回答由当
10、回答由may 引起的问题时，否定答语要用引起的问题时，否定答语要用must not,表示表示“不许可不许可”、“不应该不应该”、“不不行行”。May I come in?Yes,you may.No,you cantNo,you may not.No,you mustntNo,youd better not.will和和would：1.will是助动词或是情态动词？是助动词或是情态动词？will用于构成将来时是助动词。用于用于构成将来时是助动词。用于表示表示“意志意志”“”“决心决心”“”“请求请求”是情态是情态动词。动词。would亦同理。亦同理。eg.Iwilltellyousomethi
11、ngimportant.我要告诉你一些重要的事。我要告诉你一些重要的事。（助动词）（助动词）WillyoutellherthatImhere?请您告诉她说我在这儿，好吗？请您告诉她说我在这儿，好吗？（情态动词）（情态动词）lIf you give him time,Tom will talk and talk for hours.lEvery Saturday evening they will play chess togetherlThe door wont openlIll do my best to help you.lWill you please give me a message
12、 when you see him?l-Write to me when you get home.l-I will经常性习惯性经常性习惯性“老是、总是、终归是老是、总是、终归是表示功能，译作表示功能，译作“能能”或或“行行”意愿意愿2人称，询问对方意愿或向对人称，询问对方意愿或向对方提出请求方提出请求回答祈使句回答祈使句Would表示有礼貌的请求或邀请（表示有礼貌的请求或邀请（2人称）人称）Wouldyouhelpus,please?请您帮助我们，好吗？请您帮助我们，好吗？WhenIhadsometrouble,hewouldencourageme.Wealltriedtoatophimsm
13、okinginbedbuthewouldntlisten.过去的习惯过去的习惯意愿意愿“要；愿要；愿”Would 与与 Used to do 区别区别 “过去常常过去常常”Would -过去习惯的动作动作（现在有可能还有此习惯）Used to do -过去习惯的动作动作及状态（现在已经没有此习惯）e.g.He would get up at 8 a.m.(现在有可能还在坚持此习惯)e.g.He used to get up at 8 a.m.（现在已经不再坚持此习惯）动作动作e.g.There used to be an old building here when I was young.状
14、态状态shall和和should：1.shall用于构成将来时是助动词。用于构成将来时是助动词。shall用于征求对方的意见，表示用于征求对方的意见，表示“决心决心”是情态动词。是情态动词。eg:PerhapsIshallpayavisittoEnglandthiswinter.可能今年冬天我会去英国观光。可能今年冬天我会去英国观光。（构成一般将来时（构成一般将来时,助动词）助动词）Shallwegobytrain,Mom?妈妈，我们乘火车去好吗？妈妈，我们乘火车去好吗？（用于征求对方的意见，情态动词）（用于征求对方的意见，情态动词）Ishallgoatonce.我必须立即去。我必须立即去。（
15、表（表“决心决心”，情态动词），情态动词）l1)用于第一、用于第一、三人称征求对方的意见，三人称征求对方的意见，lWhat shall I wear on the journey?lShall we dance?l2)shall 用于第二、三人称时表允诺，警告，用于第二、三人称时表允诺，警告，命令，威胁。命令，威胁。“必须，应该可以必须，应该可以”lIf he passes the examination,he shall have a holiday.lYou shall have it back tomorrow.l3）用于第二、三人称用于法律法规条例等）用于第二、三人称用于法律法规条例等
16、文件中的要求。文件中的要求。“应该、必须应该、必须”lIts required in our regulation that students shall go to school on time.lPersons under 18 shant be employed in night work.l2.should表示义务、建议、劝告等，意为表示义务、建议、劝告等，意为“应该应该”。(oughtto)lStudentsshouldrespectteachers.lTheboysshouldntbeplayingfootball;theyshouldbeatschool.lIts4:30,The
17、yshouldbeinNewYorkbynow.lHeoughttosucceed,asheissodiligent.lItisstrangethatitshouldbesohottoday.lIdontunderstandwhysheshouldhavemadesuchamistake.lShoulditraintomorrow,themeetingwillbepostponed.劝告、建议劝告、建议义务、责任义务、责任常规、常理的推测（正常情况下）按理应该常规、常理的推测（正常情况下）按理应该居然，居然，竟然竟然与疑问词连用，表示意外、纳与疑问词连用，表示意外、纳闷、惊讶等闷、惊讶等“究竟
18、是，到底究竟是，到底”用于条件句中用于条件句中“万一万一”must和和haveto1.must用于一般问句中用于一般问句中,肯定回答用肯定回答用must否定式用否定式用neednt或或donthaveto，做做“不必不必”,mustnt表示表示“禁止，不允禁止，不允许许”MustIfinishallassignmentsatatime?Yes,youmust.No,youneednt.IdontlikethisTVset.Wemustbuyanewone.Therewasnomorebus.Theyhadtowalkhome.2.表示表示“必须必须”这个意思时，这个意思时，must和和have
19、to稍有区别。稍有区别。must着重说明主观着重说明主观看法，看法，haveto强调客观需要。另外，强调客观需要。另外，haveto能用于更多时态。能用于更多时态。Youmustbethenewteacher.Hemustbejoking.Thereisnobodyhere.Theymusthaveallgonehome.3.must表示对某人某事的猜测，表示对某人某事的猜测，作作“准准是是”，“一定一定”，一般用于肯定句中。对，一般用于肯定句中。对过去发生的事情作肯定判断用过去发生的事情作肯定判断用musthavedoneHemustcomeandworryherwithquestion,j
20、ustwhenshewasbusycookingthedinner.Ofcourse，afterIgavehermyadvice，shemustgoanddotheopposite.How old are you,madam?If you must know,Im twice my sons age.4.must表示表示“偏要，硬要偏要，硬要”，指做令人，指做令人不快的事情不快的事情need 与与 dare 实义动词实义动词情态动词情态动词实义动词实义动词 vs 情态动词情态动词肯定句肯定句 实实情情e.g.She needs to stay at home today.e.g.He dare
21、s to jump from the high wall.e.g.She need stay at home today.e.g.He dare jump from the high wall.疑问句疑问句 e.g.Does she need to stay at home today?e.g.Does he dare to jump from the high wall?e.g.Need she stay at home today?e.g.Dare he jump from the high wall?实实情情否定句否定句Dare 作为实意动词的时候，作为实意动词的时候，否定句否定句中的中
22、的 to 可以省略可以省略e.g.He doesnt dare(to)jump from the high wall.实实e.g.She doesnt need to stay at home today.e.g.He doesnt dare to jump from the high wall情情e.g.She neednt stay at home today.e.g.He dare not jump from the high wall.l1.It must have rained last night,for the streets are wet.l2.It is 8 oclock.
23、they may have arrivedl3.He looks very happy.He might not have known the resultl4.He could not have done such a thing.l5.She didnt come to school yesterday.Can she have been ill?l6.They left here early and should have arrived by now情态动词表推测情态动词表推测 对过去情况的推测对过去情况的推测l7.you might have written the letter w
24、ithout my reminding you of it.l8.The doctor could have avoided the accidentl9.you should have finished the task yesterday.l10I was really anxious about you.you shouldnt have left home without a wordl11.He ought not to have told me your secret,but he meant no harm过去本可能（不用过去本可能（不用may)过去本能够过去本能够却没有却没有过
25、去本应该过去本应该却没有却没有过去本不该过去本不该过去本不该过去本不该lIt was not cold yesterday.I neednt have taken the thick sweaters outlIt was not cold yesterday.I didnt need to take the thick sweaters out过去本不必过去本不必,却做了却做了.过去不必做过去不必做,实际也没有做实际也没有做l表推测的情态动词句子的反意疑问句表推测的情态动词句子的反意疑问句He must/may be in the room,isnt he?He cant be in the
26、 room,is he?He must have finished the work,hasnt he?He may have done the work last night,didnt he?He must have been caught in the heavy rain last night,_lwasnt he1.-_Igoouttoplay,mum?-No,you_.Youshoulddoyourhomeworkfirst.A.Might;wouldntB.May;hadbetternotC.Must;mustntD.Need;mustntBPractice 2.-Whereis
27、Emma?-Icantsayforsurewheresheis,butshe_beoutshopping.A.canB.shouldC.mustD.mayD3.Theroomisinaterriblemess;it_cleaned.A.canthavebeenB.couldntbeC.mayhavebeenD.wouldbeA4.How_yousaythatyoureallyunderstandthewholestoryifyouhavecoveredonlypartofthearticle?A.canB.mustC.needD.mayA5.There_beanydifficultyabout
28、passingtheroadtestsinceyouhavepractisedalotinthedrivingschool.A.mustntB.shantC.shouldntD.needntC6.-Therewerealreadyfivepeopleinthecarbuttheymanagedtotakemeaswell.-It_acomfortablejourney.()A.cantbeB.mustnthavebeenC.shouldntbeD.couldnthavebeenD7.Thefirespreadthroughthehotelveryquicklybuteveryone_getou
29、t.()A.hadtoB.wouldC.couldD.wasabletoD8.Peter_comewithustonight,butheisntverysure.A.mustB.canC.mayD.willC9.-CouldIcallyoubyyourfirstname?-Yes,you_.A.willB.couldC.mayD.mightC10.Sorry,Imlate.I_haveturnedoffthealarmclockandgonebacktosleepagain.A.mightB.shouldC.canD.willA11.-Excuseme,butIwanttouseyourcom
30、putertotypeareport.-You_havemycomputerifyoudonttakecareofit.A.shantB.mightnotC.needntD.shouldntA12.-WhencanIcomeforthephotos?Ineedthemtomorrowafternoon.-They_bereadyby12:00.A.canB.shouldC.mightD.needB13.Withsomuchworkonhand,you_toseethegamelastnight.A.mustntgoB.couldhavegoneC.shouldntgoD.shouldnthavegoneD14.Johnny,you_playwiththeknife,you_hurtyourself.A.wont;cantB.mustnt;mayC.shouldnt;mustD.cant;wouldntB15.Thereisnolightinthedormitory.Theymusthavegonetothelecture,_?A.didnttheyB.donttheyC.mustnttheyD.haventtheyD16.Imissedthebus,soI_gohomeonfoot.A.mustB.mayC.canD.hadtoD
