情态动词can,may,must的用法[1].

情态动词Can，could,may,might,must,haveto,need,shall,should,will,would一、can的用法1.Icanliftthestone.2.Youcanborrowmybiketomorrow.3.Canitbetrue?4.Hecanbeathomenow.5.Themooncan’talwaysbefull.1.能力：“能，会”2.许可，请求“可以”用于疑问句中用来提出要求，用于否定句表示不允许。Can…?回答用：yes,..can./withpleasure./no,…can’t.3.猜测（用于疑问句、否定句）可能…can’t不可能can与beableto的区别can有现在时、过去时（could）；可用于被动语态。beableto有各种时态；指某一次动作；不可用于被动语态。1.HesayshewillbeabletobehomeforChristmas.2.Iwasabletohelpyouyesterday.3.Thisproblemcanbesettledatonce.二、Could的用法1.表示过去有过的能力和可能性“can的过去形式”2.表示委婉礼貌的请求，常用来提问，表示“可以…”。问句回答常为：yes,…can./no,…can’t.3.Could表示推测：“可能”CouldyouspeakEnglishthen？那时你能讲英吗？Hesaidhecouldn‘tfollowme.他说他跟不上我。Icouldcomeearlier,ifnecessary.如果必要我可以早点来。—Couldyouletmehaveyourpassport?—Yes,hereitis.三、may的用法1.Youmaygohomenow,Susan.2.Youmaynotsmokeintheclassroom.3.MayIsitdown?—Certainly./Yes,please./Whynot?/Sure.—No,Iamsorry./I’mafraidyoucan’t.4.Imayborrowthisbook,mayn’tI?1.许可表示许可时，无甚区别，may较正式，can较口语化。could/might则是一种委婉的表达May/might….?回答：yes，…may./no,…can’t.2.猜测、可能性（用于肯定句或否定句中）maynot可能不1.Thestorymayormaynotbetrue.2.Canthatbetrue?Maythatbetrue?3.Hecan’tknowthetruth.Hemaynotknowthetruth.他不可能知道真相。他可能不知道真相。Might也可表示推测，同may，不是其过去式形式，而是比may更委婉的推测。可能性也更小四must的用法1.Youmustgetupmuchearlier.2.Youmustnotspeakillofothers.3.Mustwewashthedishesatonce/Yes,youmust.No,youneedn’t./youdon’thaveto.1.必须、一定(主观看法)mustn’t不准，禁止2.猜测（用于肯定句）否定：can’t/couldn’t不可能Must…?的回答：yes,…must.no,…needn’t/don’thaveto.It’s10o’clock.Mymothermustbeangry.itcan’tbeadog.Wethoughtourteachermustbejoking.五.haveto的用法表示客观需要“不得不，必须”Imissedthetrain,soIhadtotakeataxi.在疑问句和否定句中，haveto多用助动词do构成，Didhehavetodoit?Youdon‘thavetogothere.（不需要）六need的用法后加动词原形表示需要，必须，用于否定和疑问句否定：needn’t（不需要），疑问将need提前注：用于肯定句时，常作实意动词用：needtodosthNeedwereturnthemagazinestoday？yes，youmust./no,youneedn’t.Youneednotdothis。疑问句回答：同must七.Shall的用法1)Shallthosegoodsbesentovertoyouatonce?2)Shallwehelpyou?3)shalltheboycomeatonce?1.表示说话者的意图、允许、警告、命令、决心等，用于陈述句的第二、第三人称中，有必须，应，可之意。例如：1）Youshallhavethatbooktomorrow.2)Heshallbepunishedifheinsistsondoingthat.2.在问句中表示征求对方意见，主要用于第一、第三人称，有“…..好吗”，“要不要”等意思。回答：yes,…can/may.no,…can’t.八.Should的用法1.表示劝告，建议，义务，责任。“应该”Youshouldkeepyourpromise.你应该遵守诺言。Weshouldlearnfromeachother.Youshouldgiveupsmoking.2.表示推断时意为“应该”、“可能”：should表示推断时，语气较肯定，通常是指非常可能的事(因为暗示有一定的事实依据或合乎常理)，而may,might,could等表示推测时，则语气较不肯定，尤其是might,could。1）Theyshouldbetherebynow,Ithink.2）WhencanIcomeforthephotos?Ineedthemtomorrowafternoon.They_____bereadyby12:00.A.canB.shouldC.mightD.need九.Will和would的用法1.表示意愿will表示现在的意愿，would表示过去的意愿。SheaskedifIwouldgowiththem.2.表示征求意见或提出请求主要用于第二人称的疑问句中，will和would均可用，would此时并不表过去，而表示委婉语气。Will[would]youpleaseposttheletterforme?Wouldyoulikesomefood?回答:yes,…will./sure.no,…won’t./no,thanks.Iwillpayyouatthepriceyouask.Hewouldn’thelpmeyesterday.习题：1.-Mum，mayIwatchTVnow？-Sure，butyou________helpmewithmyEnglish.A.canB.mayC.mustD.could2.-________Idownloadthearticleagain？-No，youneedn't.A.ShallB.WillC.MustD.Can3.-Canyougoskatingwithusthisafternoon？-Sorry，Ican't.I________takecareofmylittlesisterathome.A.canB.mayC.wouldD.haveto4.-MustIhandinmyexercisebooktoday？-No,you________.A.can'tB.needn'tC.mustn'tD.won't5.-MayIhaveawordwithyou？-No,you________.I'mbusytoday.A.needn'tB.wouldn'tC.don'thavetoD.can't6.-________IhaveyourEnglishname，please？-Yes，Helen.H-E-L-E-N.A.MustB.MayC.WillD.Need7.-Whoistheboyoverthere？IsitJohn？-No，it________behim.Johnismuchtaller.A.mustn'tB.maynotC.can'tD.needn't8.-CanyouplayFrisbee，Jay？-Yes,I________.It'seasy.A.mustB.canC.needD.may9.-Youmustcomebackeverymonth.-Yes，I________.A.willB.mustC.shouldD.can10.She________knowtheanswer，butI'mnotsure.A.maybeB.maybeC.mayD.must11.-Mustwecleantheroomrightnow？-No,you____.You____cleanitafterlunch.A.needn’t；mayB.needn't;mustC.Mustn't；canD.mustn't；may12.John________cometoseeustonight,butheisn'tverysureyet.A.mayB.canC.hastoD.must13.Children________playwithfire.A.mustn’tB.can'tC.shouldn'tD.needn't14.-________Icomein，Mr.Green？-Yes,comein，please.A.MustB.NeedC.WillD.May15.-MustIfinishtheworktoday？-No，you________.You________finishittomorrow.A.mustn't；mayB.can't；canC.needn’t；mayD.needn't；must