情态动词和虚拟语气

高考资源网（ks5u.com）您身边的高考专家版权所有@高考资源网八、情态动词和虚拟语气情态动词I.情态动词基本用法情态动词用法否定式疑问式简答式can能力（体力，智力，技能）允许或许可（口语中常用）可能性（表猜测，用于否定句或疑问句中）cannot/cannot/can’tdoCan…do…?Yes,…can.No,…can’t.couldcouldn’tdomay可以（问句中表示请求）可能，或许（表推测）祝愿（用于倒装句中）maynotdoMay…do…?Yes,…may.No,…mustn’t/can’t.mightmightnotdoMight…do…?Yes,…mightNo,…mightnot.must必须，应该（表主观要求）肯定，想必（肯定句中表推测）mustnot/mustn’tdoMust…do…?to.Yes,…must.No,…needn’t/don’thavehaveto只好，不得不（客观的必须，有时态和人称的变化）don’thavetodoDo…havetodo…?Yes,…do.No,…don’t.oughtto应当（表示义务责任，口语中多用should）oughtnotto/oughtn’ttodoOught…todo…?Yes,…ought.No,…oughtn’t.shall用于一三人称征求对方意见用于二三人称表示许诺、命令、警告、威胁等shallnot/shan’tdoShall…do…?Yes,…shall.No,…shan’t.should应当，应该（表义务责任）本该（含有责备意味）shouldnot/shouldn’tdoShould…do…?will意愿，决心请求，建议，用在问句中would比较委婉willnot/won’tdoWill/Would…do…?Yes,…will.No,…won’t.wouldwouldnot/wouldn’tdodare敢（常用于否定句和疑问句中）darenot/daren’tdoDare…do…?Yes,…dare.No,…daren’t.need需要,必须（常用于否定句和疑问句中）neednot/needn’tdoNeed…do…?Yes,…must.No,…needn’t.usedto过去常常（现在已不再）usednot/usedn’t/usen’ttododidn’tusetodoUsed…todo…?Did…usetodo…?Yes,…used.No,…use(d)n’t.Yes,…did.高考资源网（ks5u.com）您身边的高考专家版权所有@高考资源网No,…didn’t.II.情态动词的重点知识表示“能力、许可”的can和may表示能力的情态动词用can/couldAcomputer_____thinkforitself;itmustbetoldwhattodo.A.can’tB.mustn’tC.maynotD.mightnot表示许可时用may/might,can/could都可以，但在问句中用could…?或might…？以使口气委婉客气，其回答一定要用can或may，以使回答口气明确（must表示一定，必须，mustn’t表示禁止，不许可）。①—CouldIcallyoubyyourfirstname?—Yes,you______A.willB.couldC.mayD.might②Johnny,you_____playwiththeknife,you_____hurtyourself.A.won’t/can’tB.mustn’t/mayC.shouldn’t/mustD.can’t/shouldn’t在肯定句中could不可以用来表示过去某一特定场合的能力，而要用was/wereableto。Thefirespreadthroughthehotelveryquicklybuteveryone_____getout.A.hadtoB.wouldC.couldD.wasableto表示“推断、判断”的canmay,must在肯定句中都可以用来表示可能。在含义上must语气最肯定,may表示的是事实上的可能性。Peter______comewithustonight,butheisn’tverysureyet.A.mustB.mayC.canD.will而can表示的是逻辑上的可能性：Maryisinpoorhealth.Shecanbeillatanytimes.在否定句中只能用can和may。所以can’t时用以代替mustn’t，语气比may更肯定。中文可以翻译为不可能。Michael______beapoliceman,forhe’smuchtooshort.A.needn’tB.can’tC.shouldD.may在疑问句只能用can，不能用may和must。Hemaybeverybusynow.Canhebeverybusynow?Hemustbeverybusynow.Canhebeverybusynow?needneed作为情态动词只有一种形式，只用于否定句和疑问句。daredare作为情态动词用时有两种形式：dare和dared两个词形，除了可以用于否定句和疑问句外，还可以用于条件从句或表示怀疑的句子中。Ifhedarecome,Iwillkickhimout.Idon’tknowwhetherhedaresay.注意:Hedoesn’tdare(to)answerthequestion.（否定句）Doesshedare(to)enterthedarkroom?（疑问句）shall用于第一人称：征求对方的意见。Whatshallwedothisevening?用于第二、三人称：警告、命令、允诺、威胁等。Youshallfailifyoudon’tworkharder.警告HeshallhavethebookwhenIfinishreading.允诺Heshallbepunished.威胁should劝告、建议、命令、应该做、道义上的责任。Youshould(oughtto)gotoclassrightaway.高考资源网（ks5u.com）您身边的高考专家版权所有@高考资源网Ishould(oughtto)helphimbecauseheisintrouble.will/would请求、建议，would比will委婉客气。Wouldyoupassmethebook?表示意志、愿望和决心。Iwillneverdothatagain.Theyaskedusifwewoulddothatagainwould可表示过去反复发生的动作或某种倾向。DuringthevacationhewouldvisitmeeveryweekThewoundwouldnotheal.（伤口老是不能愈合）would表示估计或猜想。Itwouldbeabouttenwhenhelefthome.Whatwouldshebedoingthere?情态动词+havedone的用法could+havedone：本可以做而实际上未能做。Youcouldhavedonebetter,butyoudidn’ttryyourbest.cannot+havedone：表示对现在或过去行为的否定推测。Hecannothavebeentothattown.can+主语+havedone：表示对过去行为的怀疑或不肯定（用在疑问句中）。Canhehavegotthebook?might(may)+havedone：对过去发生的行为不太肯定的推测。Hemaynothavefinishedthework.Ifwehadtakentheotherroad,wemighthavearrivedearlier.must+havedone：对过去发生的行为肯定的推测。其否定式为：cannothavedone。Youmusthaveseenthefilm.Youcannothaveseenthefilm.needn’t+havedone：本来不必要做的而实际上又做了。Youneedn’thavewateredtheflowers,foritisgoingtorain.注意：didn’tneedto(haveto)do：没有必要做而实际上也没有做Ididn’tneedtocleanthewindows.Mysisterdidit2hoursago.should(oughtto)+havedone：本来应该做而实际上又没有做。其否定形式表示某中行为不该发生却发生了。Youshouldhavestartedearlier,butyoudidn’t.Sheshouldn’thavetakenawaymymeasuringtape,forIworkedtouseit.注意：Heshouldhavefinishedtheworkbynow.（表推测）虚拟语气类别用法例句If引导的条件从句与现在事实相反从句动词：过去式（be用were）主句动词：should/would/could/might+doIfhewerehere,hewouldhelpus.与过去事实相反从句动词：had+done主句动词：should/would/could/might+have+doneIfIhadbeenfree,Iwouldhavevisitedyou.高考资源网（ks5u.com）您身边的高考专家版权所有@高考资源网与将来事实相反从句动词：过去式/should+动词原形/were+todo主句动词：should/would/could/might+动词原形Ifitshouldraintomorrow,wewouldnotgocamping.省略if的虚拟条件句将虚拟条件从句中的were，had,should放到主语之前，构成主谓倒装①Shouldhecome,tellhimtoringmeup.②WereIyou,Iwouldnotdoit.③HadIbeenfree,Iwouldhavevisitedyou.混合虚拟条件句不同时间的虚拟：各遵守各的规则①Ifhehadlistenedtome,hewouldnotbeintroublenow.②Ifhehadtoldmeyesterday,Ishouldknowwhattodonow.③IfIwereyou,Iwouldhavegonetoherbirthdayparty.虚拟与陈述的混合：各遵守各的规则①Hecouldhavepassedtheexam,buthewasn’tcarefulenough.②Youshouldhavecomeearlier.Thebusleftamomentago.含蓄虚拟条件句butfor+名词表示虚拟条件句子或主句中的谓语动词的形式视具体情况而定。这是考查考生应变能力的最佳试题。---Butforyourtimelywarning,we______intogreattrouble.---Youknowwe’refriends.A.wouldgetB.musthavegotC.wouldhavegotD.can’thavegotwithout+名词表示虚拟条件Withouttheairtoholdsomeofthesun'sheat,theearthatnightwouldbefreezingcold.动词不定式表示虚拟条件Itwouldbeonlypartlyrighttofollowinthisway.如果用这种方式，仅仅对了一半。现在分词表示虚拟条件Havingknownintime,wemighthavepreventedtheaccident.要是及时得知的话，我们也许能阻止这场事故。过去分词表示虚拟条件Givenmoreattention,thetreecouldhavegrownbetter.如果多留心