情态动词（新)

情态动词用法,一、can/could,1.表能力（体力、知识、技能）。Canyouliftthisheavybox?（体力）Marycanspeakthreelanguages.（知识）Canyouskate?（技能）此时可用beableto代替。Can只有一般现在时和一般过去式；而beableto则有更多的时态。注：当表示“经过努力才得以做成功某事”时应用beableto，不能用Can。如：Hewasabletogotothepartyyesterdayeveninginspiteoftheheavyrain.,2.表示请求和允许。-CanIhaveawordwithyou?-Yes,youcan./No,youcant.此时可与may互换。在疑问句中还可could,might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。-CouldIcometoseeyoutomorrow?-Yes,youcan.(No,Imafraidnot.),3.表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。Canthisbetrue?Thiscantbedonebyhim.Howcanthisbetrue?,4.表示理论上的可能性，用于肯定句。常和sometimes,attimes连用。Itishotinsummerhere,butsometimesitcanbecool.5.用于句型：cannot/nevertoo/enoughYoucantbetoocarefulwhiledriving.Icantthankyouenough.,二、may/might,1.表示请求和允许。might比may语气更委婉，而不是过去式。否定回答时可用cant或mustnt，表示“不可以，禁止”。1)-Might/MayIsmokeinthisroom?-No,youmustnt.2)-May/MightItakethisbookoutoftheroom?-Yes,youcan.(No,youcant/mustnt.)用MayI.？征徇对方许可时比较正式和客气，而用CanI.？在口语中更常见。,2.表示推测、可能性（不用于疑问句）。might不是过去式，它所表示的可能性比may小。Hemay/mightbeverybusynow.Yourmothermay/mightnotknowthetruth.注：maynot可能不cannot不可能,3.用于祈使句，表示祝愿。Mayyousucceed!=Wishyousuccess!4.may/mightaswell./wellYoumay/mightaswellhavearest.Youmay/mightwellpasstheexam.,三、will/would,1.表示请求、建议等，would更委婉。Will/Wouldyoupassmetheball,please?2.表示意志、愿望和决心。Iwillneverdothatagain.Theyaskedhimifhewouldgoabroad.,3will表示现在的习惯；would表示过去反复发生的动作或某种倾向。（would表示过去习惯时比usedto正式，且没有“现已无此习惯”的含义。）Duringthevacation,hewouldvisitmeeveryotherday.Iwillhaveawalkafterluncheveryday.,4.表示主语的某种属性。Thedoorwontopen.Theenginewontstart.5.表示某种趋势。Withoutwater,fishwilldie.,四、must,1.表示必须、必要。1)Youmustcomeintime.2)-Mustwehandinourexercisebookstoday?-Yes,youmust.-No,youdonthaveto/youneednt.,2.mustnt表“禁止”Youmustntplaywiththeknife.3.(表固执、不满等)偏偏；硬要；偏要Ifyoumustknow,Imgoingtohelphimlookforanapartment.Mustyouinterruptmenow?Mustyoumakealoudnoise?,4.表肯定推测。must+v对现在的肯定推测;must+havedone对过去的肯定推测。Thelightison.Ourteachermustbeintheoffice.Thegroundiswet.Itmusthaverainedlastnight.Yourmothermustbewaitingforyounow.注:musthavedone的反义：cant/couldnthavedone,五、shall,1.用于一般疑问句中,与第一、三人称连用,表示征求对方的意见Shallwegooutforawalk?Shallhehaveatry?【注】may用于征求对方的许可,shall用于征求对方的意见或指示.MayIhavealook?我能看一下吗?ShallIhavealook?要我看一下吗?,2.用于第二、三人称,表示说话人的命令、警告、强制、允诺、威胁或决心等Dontworry.Youshallgettheanswerthisveryafternoon.Heshallbesorryoneday.Itellyou.,3.用于法律、规则等条文中)应,须,得Thefineshallbegivenincash.Accordingtotheregulations,thestudentsshallgotobedby10oclockintheevening.,六、should,1.(表义务、责任)应该Weshouldattendthemeeting.2.表推测“理应”。Heshouldbehomebynow.3.(表惊讶、遗憾)竟然；居然Itwassadtomethatthey,sopoorthemselvesshouldbringmefood.,4.表示感情色彩。常和how,why连用。HowshouldIknow?Whyshouldntyouinvitehim?5.用于虚拟语气中.Shouldyouhaveanyquestions,pleaseletmeknow.Isuggestthatyoushouldcomenow.Takeanumbrellaincaseitshouldrain.,七、dare/need,1.dare作情态动词用时,常用于疑问句、否定句和条件从句中,过去式形式为dared。（不能用于肯定句）HowdareyousayImunfair?HedarentspeakEnglishbeforesuchacrowd,darehe?Ifwedarednotgotherethatday，wecouldntgetthebeautifulflowers.,Idarentgooutatnight.=Idontdare(to)gooutatnight.Dareyougooutatnight?=Doyoudare(to)gooutatnight?,2.need作情态动词用时,常用于疑问句、否定句。在肯定句中一般用must,haveto,oughtto,should代替。Youneedntcomesoearly.-NeedIfinishtheworktoday?-Yes,youmust./No,youneednt.,Ineedntdothehomeworknow.=Idontneedtodothehomeworknow.NeedIdothehomeworknow?=DoIneedtodothehomeworknow?,注：didntneedto/neednthavedone区别Hedidntneedtowaitforme.Heneednthavewashedthecarbecauseitrainedyesterday.,巩固,1.YoudidntwaitforMr.Blacklastnight,didyou?-No,butwe_.Hedidntreturnhomeatall.A.neednthaveB.didntneedto,B,2.YoudidntwaitforMr.Blacklastnight,didyou?-Yes,butwe_.Hedidntreturnhomeatall.A.neednthaveB.didntneedto,A,八、情+V/情+havedone表推测,1.情V”结构通常用来对现在或将来的状况进行推测.Thelightisstillon.Hemustbeworkingintheofficenow.Michaelcantbeapoliceman,forhesmuchtooshort.Hemaybeintheclassroom.Illgoandmakesure.,2.“情态动词havedone”结构用于对过去事情的推测.Ididnthearthephone.Imusthavebeenasleep.Tomhasntcomebackyet.Hemayhavemissedthebusagain.Jackcanthavearrivedyet；otherwisehewouldhavetelephonedme.,【注】mighthavedone和couldhavedone除了表对过去事情的推测外,还可表示一种责备语气,意为“(过去)本来可以(能够)做某事,但实际上没有做到”,此时不能用may或can.Hecould/mighthavepassedtheexam,buthedidntworkhard.,巩固,1.-Therewerealreadyfivepeopleinthecarbuttheymanagedtotakemeaswell.-It_acomfortablejourney.A.cantbeB.shouldntbeC.mustnthavebeenD.couldnthavebeen,D,2.Jenny_havekeptherword.Iwonderwhyshechangedhermind.A.mustB.shouldC.needD.would,B,3.-WhatareyoudoingthisSaturday?-Imnotsure,butI_gototheRollingStonesconce