情态动词的特点

Grammar:ModalverbsLecturedbyRenQiuyu一、情态动词的特点1有词义2没有人称和数的变化。也就是说，它在任何主语后形式都是一样的，这是情态动词和助动词最大的差异。3有时态的变化4不能独立作谓语，后面必须跟动词原形在情态动词后一般要跟不带to的不定式（oughtto除外）二、情态动词的种类原形过去式词义同义词组cancould能够beabletomaymight可以、也许mustmust必须havetohavetohadto必须、不得不musthadbetterhadbetter最好可以是实义动词和情态动词needneeded需要daredared敢于shallshould应该oughttowillwould愿意usedto过去常常oughttooughtto应该should1)can表示体力、智力上的能力。否定式为cannot,缩略为can’t;过去式为couldcouldn’teg:Wecandothingstheycan’tdo.Marycantypewellandhermothercouldtypewellwhenshewasyoung.2)表示客观可能性eg:Mancannotlivewithoutair.3)表示征求意见或请求许可，表示语气委婉eg:CanIgoforaswimthisafternoon,Mum?Couldyoulendmeyourbicycle?No,sorry,Ican’t.(couldn’tiswrong)Yes,ofcourseyoucan.1.can和could4)can和could表推测（can用于否定及疑问,could肯定、否定、疑问皆可）can(could)not+V原（link.或状态动词）对现在状态的推测can(could)not+be+doing对现在动作的推测can(could)not+havedone对过去动作的推测eg:a.Theyounggirlcan’tbeournewchairman.Can/Couldthenewsbetrue?b.Hecan’tbereadinginthereadingroom,forIsawhiminthestreetjustnoTheymaybearguing.ButIaminterestedinwhattheycan/couldbearguing.c.Theroadisn’twet.Itcan’t/couldn’thaverainedlastnight.Idon’tknowwhyshedidn’tcallmeyesterday.Can/Couldshehaveforgottenmytelephonenumber?5)couldhavedone本能做却没有做,canhavedone这种结构不存在eg:Youcouldhavecaughtthefirsttrain,butyougotuptoolate.6)Can/could与beableto的区别A.beabletodosth.也表示能力，可以用于不同时态，前后还可以用情态动词must,may,might以及seemto,usedto,appearto等，而can/could只用于一般现在时和一般过去.eg:Heisableto(=can)playthepianoverywell.Afterthreeyearsofhardwork,hewasabletopasstheentranceexamination.Thelargehallwillbeabletohold5000audience.Heseemstobeabletoworkoutthepuzzlingquestion.B.当用于过去时态时，could表示能力，但有没有做，不知；而was/wereableto指过去某种具体的能力，通过努力并做成功了，相当于managedto或succeededineg:HecouldsingmanyEnglishsongs.It’sknownthathewasabletorecitemanyforeignpoemsatsix.1)may表示请求许可。疑问式MayI....?多为请求允许，通常用于正式文体egMayIcomein?No,youcan’t/maynot.Yes,please.No,youmustn’t.(强烈禁止，不允许)Yes,certainlyPleasedon’t.Sure.Might也可以表示允许，MightI?和MayI...?用法相近.但might表示请求语气迟疑委婉，回答时应用may表示肯定eg:---MightIaskforaphotoofyourfamily?---Yes,youmay.2)may用在句子开头，表示祝愿May+主语+动词原形+其它成分eg:Mayyousucceedinthecomingexamination!Mayallyourdreamscometruesomeday!2.may和might3)may和might表推测（不用于疑问）may/might+V(系动词或状态性动词)对现在状态的推测may/might+bedoing对现在动作的推测may/might+havedone对过去动作的推测eg:a.HemayknowAlice’saddress.HemaynotknowAlice’saddress.（可能不）Hecan’tknowAlice’saddress.（不可能）Canitbetrue?Itmaybe,ormaynotbe.b.Where’sTom?Hemay/mightbeplayingfootball.c.---Heseemsknowthecityquitewell.---Hemay/mighthavebeentherebefore.1)表示必要性、义务，“应该”、“必须”的意思，否定式mustn’t表示不允许egYoumustwaitforyourturn.Youmustn’tjumpthequeue.MustIbehomebeforeeighto’clock?---Yes,youmust.(No,youneedn’t./No,youdon’thaveto.)2）haveto和must意义相近，意为“不得不”，含有“客观需要使得必须这样做”的意思，有时态、人称的变化,havegotto用于口语，don’thaveto为否定式，意为“不必要”egShedidn’thavetosaysorry.Dowehavetoanswerallthequestions?NextyearIwillhavetoleavethisschool.3）must表推测（一般用于肯定句）意为：一定否定式：can’tmust+Vmust+bedoingmust+havedoneeg:情态动词must猜测性的反义疑问句Hemustbeadoctor,isn’the?（表现在状态，用be）Hemustlivenearhere,doesn’the?（表现在动作，用do,does）Hemusthavecomehereyesterday,didn’the?（表短暂性过去动作，用did）TheymusthavebeentoBeijing,haven’tthey?（表现在状态，用have,has）3must和haveto4will/would;shall1)will表示意志意愿，用于各种人称，可译为“肯”、“会”、“愿意”等，过去式为wouldegIfyouwillallowme,Iwillseeyouhome.Iwillhavenothingtodowiththismatter.Nomatterwhathappened,hewouldn’tsayaword.Ifhekeptonmakingmistakes,Iwouldn’tmakefriendswithhim.2)will用于第二人称，表示有礼貌的请求，would为过去式，但语气更委婉egWillyoukindlyhandmethewatch?Bringthefruittothedining-room,willyou?---Wouldyoudomeafavor?---Yes,Iwill./Sure/Ofcourse/Certainly.No,Iwon’t./I’msorryIcan’t.Will/Wouldyoupleasedo…Wouldyouliketodosth.wouldratherdosth.(thandosth.)3)woulddo(usedtodo)表示过去常常做某事,would后只能接动作性动词而usedto既可以接动作性动词，也可以接状态性动词。Hewouldgotoenjoysomewonderfulfilmsatnight.Heusedtobeateacher.4)wouldhavedone用于虚拟，与过去事实相反Ifyouhadhelpedus,wewouldhavefinishedourhomeworkaheadoftime.5）shall用于第一、第三人称疑问句中，表示说话人征求对方意见或向对方请示。egShallwegoandgetsomefood?Whenshallhebeabletoleavethehospital?Shall用于第二、第三人称，表示说话人给对方的命令、警告、允诺或威胁。eg.Youshalldoit./Heshallstayathome.（命令）Youshallfailifyoudon’tworkhard.（警告）HeshallhavethebookwhenIfinishreading.（允诺）Heshallbepunished.（威胁）5should/oughtto两者意义基本相同，用法也相同1）表示劝告或建议，should语气比oughtto弱，意为“应该”，否定式shouldn’t,oughtnotto意为“不应该”egYoushouldgeteverythingreadybeforetheexamination.Heshouldn’tbesocareless.Weoughttobeoutinthefreshair.Weoughtnottotakerisks（冒险）.2）表示应该怎么样却没有怎么样A.对现在进行动作should(oughtto)bedoing/shouldn’t(oughtnotto)bedoingeg:Youshouldbewashingyourclothes.Whyareyouplayingfootball?Youareill.Youshouldn’tbeworkinghereB.对过去动作Should(oughtto)havedone(本应该做却没有做)Shouldn’t(oughtnotto)havedone(本不应该做却做了)eg:Youshouldhavegoneoveryourlessons.Ishouldn’thaveeatensomuchicecream.3)should表推测，暗含很大的可能或有根据有把握Thefilmshouldbeverygood.Thephotoshouldbereadytomorrow.6need可以既作情态动词又作实义动词1)need用作实义动词，用在肯定句、否定句和疑问句中，有人称变化和过去时形式，后接名词、代词、动名词和动词不定式egSheneedsmorerest.Youdidn’tneedtotellhimthenews.TheTVneedsmending/tobemended.2)need作情态动词时一般只用在否定句或疑问句中，没有人称和时态的变化eg---Needwetellhimaboutit?---No,youneedn’t/don’thaveto.Youneedn’tfinishwritingthereportinsuchashorttime.Hesaidheneednotgoyesterday.