高中英语情态动词讲解

Grammar:ModalverbsHowmanymodalverbsdoyouknow?cancouldmaymightshallshouldmustwillwouldoughttohavetodare(daren’t)need(needn’t)usedto表示推测不表示推测modalverbs表示推测１．一定，肯定must一定不，不可能can’t,couldn’t２．可能肯定句may,might,could否定句may\mightnot疑问句can,could都可以+dosth.表示现在bedoing表示正在发生的动作havedone表示过去发生的动作Hemusthaveacarnow.１.must表示推测时，可以推测现在/正在发生的动作/过去发生的动作。他一定有一辆车．他一定在教室里做练习。他一定已完成了工作Hemusthavefinishedthework.Hemustbedoinghisexercisesintheclassroom.一定不，不可能can’tcouldn’tHecan`tbeathome.Hecouldn'thavesaidsuchathing.他们一定不在图书馆读书。约翰是很聪明的，他应该不会叫他儿子那样做。Theycan`tbereadinginthelibraryJohnisveryclever.Hecannothavetoldhissontodothat.２．可能肯定句could,may,might否定句may\mightnot（可能不）疑问句can,could他可能正在睡觉。Thesestudentsmay/mighthaveseenthefilmbefore.否定句Theboymay/mightnotbewatchingTVathome.（现在）这个男孩可能没在家看电视Hemay/mightbesleepingnow疑问句Howcouldhehaveforgottensuchanimportantthing?这么重要的事他怎么能忘了呢？It`ssolate.Wherecanshehavegone?天晚了，她可能去哪儿了呢？Canyouhaveleftthewatchathome?你会不会把表丢在家里呢？一.Choosethebestanswerstocompletethefollowingsentences:1.Ithoughtyou______likesomethingtoread.SoIhavebroughtyousomebooks.A.oughtB.mightC.couldD.must2.–ThatmanmustbeSarah`shusband.--No,he_____beherhusband.Sheisstillsingle.A.can`tB.mustn`tC.maynotD.oughtto3.Peter_____comewithustonight,butheisn`tverysure.A.mustB.mayC.canD.will4.–What____itbe?--It______beamailbox,foritismoving.It______beacar.A.can;can`t;mustB.can;can;mustC.can;mustn`t;mustD.must;mustn`t;can5.–Look,someoneiscoming.Guess__________.--Jack.He`salwaysontime.A.whocanitbeB.whohemayC.whohecanbeD.whoitcanbe6.–IsawMaryinthelibraryyesterday.--You_____her.Sheisstillabroad.A.mustn`tseeB.can`thaveseenC.mustn`thaveseenD.couldn`tsee7.David,you_____playwiththevaluablebottle,you_______breakit.A.won`t;can`tB.mustn`t;mayC.shouldn`t;mustD.can`t;shouldn`t表示能力一．表示能力can,could,beabletocan表示智力，体力方面的能力只能用现在或过去时。beableto通过努力克服困难作成事情,能用于各种时态。*was/wereableto:设法做成某事相当于managedtodosth.succeededindoingsth.。can与beableto用法区别常与句子时态有关1.现在时比较1)表示”能力”时,beableto不用于第二人称,Youareabletodothework,Ithink.(X)改用cancan与感官动词feel,hear,see,smell,taste连用时,can显得可有可无,因而失去了情态动词的意义,这种情况下can不能用beableto代替e.g.,Wecanseebeautifulflowersandgreentreeshereandthere.Anyonecanseeitisofnouse.3)can与某些表示意念的动词如：understand,remember,forget,hope,imagine,believe,suppose等连用时，同样没有情态动词的意义，也不可用beableto取代。e.g.Ican’tbelievetherearesomanytallbuildingsnowinmyhometown2.过去时比较was/wereableto意含”经过努力”“凭借才能”获得的”能力”常与”manageto”相通Theywereshortofmodernmachines,buttheywereabletocompletetheprojectintime.二．表示允许can,could,may,mightmight,could表达更客气、委婉、礼貌的请求语气。Excuseme,couldyoutellmethewaytothebusstation?Couldyouhelpme?Youcangonowifyoulike.MayIsmokeintheroom?三．表示必须oughtto/shouldhavetomust*haveto能用于各种时态,且有人称和数的变化.oughtto的否定式为oughtnotto或者oughtn’tto1.should和oughtto大多数情况下，含义基本相同，should主要看主观看法，oughtto更多反映客观情况，在谈到法律，规定，义务时使用。如：youshouldtryyourbesttopasstheentranceexamanations.Weoughttogoandseehellen,butIthinkwehavenotime.Should还可以表示惊讶，出乎意料的意思Whyshouldhedosuchathing?2.must与haveto的用法前者侧重于主观意念,后者则用于表示客观条件或义务,译为”只好”“不得不”e.g.,Hemustworktomakehisliving.Hehastobegforaliving.Must没有过去式,在单句中若是过去时,须用hadtoe.g.,Hebeggedfromdoortodoor,forhehadtodosotolive若在从句中,则可用must来表示过去e.g.,HesaidhemustmanagetoownanewhouseforEaster.must用于疑问句，表示责备、抱怨的感情色彩，意思为“偏要，硬要、干嘛”；四．表示虚拟１．shouldhavedone本应该做（而没做）shouldnothavedone本不应该做Heshouldn‘thavesaidsuchathing.他当时不应该说那种话。Weshouldhavestudiedlastnight,butwewenttotheconcertinstead＊这种句式也能用oughtto２．neednothavedone没有必要做某事Ineednothavegotupsoearly.我本来不必要那么早起床的（事实上早已起床）Ineednothavewaitedforthetrainforanhour.我本来不必要等一个小时的火车。（事实上已经等了一个小时）3.couldhavedone它表示“过去本来能够…”实际上没能做…。Ifyoucouldhavefinishedthetaskintime，youcouldhavebeenpromoted.如果你当时能如期完成那任务的话，你可能已提升了（实际上没有被提升）Icouldhavelaughedtohearhimtalklikethat.听他那样讲话，我差点笑出声来。4.mighthavedone虚拟式表示与过去事实相反的假没结果。Ifshehadstartedalittleearlier，shemighthavebeenintimeforthetrain.如果她早点出发，她有可能及时赶上火车。(实际上没有早出发，便没有赶上火车)Itmighthavebeenbettertostopthen.如果那时就停止的话，也许比较好。5．wouldhavedone它表示的是与过去事实相反之假设的结果，意思是“当时就会…了”而实际上没有…IwouldhavehelpedyouifIhadknownofyourdifficulties.Ifithadn‘trainedyesterday,wewouldhavegoneclimbing.假如昨天没下雨，我们就去了。（实际上没有去）。五．其他情态动词用法１情态动词dare,need通常用于否定句或疑问句Whodaredoit?Dareyougooutalone?dare,need还可用作行为动词，可以用于各种句式，后面可跟加to的不定式A.whodaredoit?B.Hedarestodoit.A.Heneedn’tdoitB.heneedstodoit上述句子中A句为含情态动词的句子，B句中dare.need均为行为动词注意动词dare的某些特殊用法。1）固定句型．Idaresay.我敢说．我猜想／以为Don’tworry,sir.Idaresay,nobodywillcomeagain2)作为行为动词dare在否定句中后面的ＴＯ可以省略．e.g:Hedoesn’tdare(to)gototheforestdoneatnight.Themanneverdares(to)doanythingwithouthisowner’spermission.5.dare“敢”，多用在否定或疑问句中。Thelittlegirldarenotspeakinpublic.小女孩不敢在公众面前说话。Dareyoucatchthelittlecat?你敢抓小猫吗?dare除用作情态动词外，更多的是当实义动词使用，用法同实义动词一样，要考虑人称，单复数，时态等。Doyoudaretowalkinthedark?你敢黑夜走路吗？Hedoesn'tdaretotelltheteacherwhathappenedthatday.他不敢告诉老师那天发生的事。２．willI.表现在经常发生的情况．e.g.,Themanwillgotoworkeveryday.(=Themangoestoworkeveryday后者更常用)Thedoorwon’topen.II.表示“决心”“意愿”“可能”等e.gIfyouwillcometonight,he’llmeetyou,Ithink.Thiswillbethebookyouarelookingfor.Willyoucomein?(=Willyoupleasecomein?)III.若表示过去，则用woulde.g.,Hewouldtakeawalkaftersupperwhenhelivedinthecountry