情态动词表推测用法总结情态动词有can,could,may,might,must,haveto,oughtto,need,dare,shall,will,should,would,beableto,及半情态动词betodo,hadbetter等16个。haveto,need,dare,shall,beableto,betodo,hadbetter等7个不用于表推测。must,will,would,oughtto,should,can,could,may,might等9个都可用于表推测。情态动词+havedone结构在特定的语境中，一些“情态动词+havedone”不再是对易发生事情作猜测，而是表达自己的看法，有时具有一定的感情色彩。1.musthavedone“过去一定做了某事”肯定句中；对过去已经发生的行为进行推测。Thelightswereout;theymusthavebeenasleep.Itmusthaverainedlastnight,didn’tit?2.couldhavedonea.肯定句子“可能已经…”;b.疑、否定句中“可能…吗？不可能…”对过去发生的行为怀疑；c.过去未曾实现的可能、能力“本来可以…却未…”a.Hecouldhavebeenkilled.b.Wherecouldhehavegone?IsawMrWangjustnow.Hecouldn’thavegonetoBeijing.c.Youcouldhavedonebetter,butyouweretoocareless.3.wouldhavedone用于与过去事实相反的虚拟语气IfIhadstudiedhard,Iwouldhavepassedtheexam.Wecouldn’thavefinishedtheworkwithoutyourhelp.5.shouldhavedone“过去本该做某事却未做”表责备Youshouldhavecometothemeetingearlier.4.mayhavedone肯定句中“也许已经..了”Hemay/mighthavegonetobed;it’s9:00.mighthavedone否定句中“可能不…”Hemaynothavefinishedthework.6.needhavedone/本来有必要做却…未做Youneedn’thavetakenataxi;foritwasverynear.needn’thavedone/本来不必做…却做了7.wouldratherhavedone本想做但没做Moreexamples:•Icouldhavecomehereearlier.Butmycarbrokedown.•Ineedn'thaveboughtsomuchwine-onlyfivepeoplecomehere.•Youshouldn'thavedonethat;Ihadwarnedyouofthatseveraltimes.•Iwouldhavehelpedyou,butIwastoobusy.•Hemay/mighthavearrivedinBeijingbynow.表示否定的情态动词的用法:部分情态动词的否定式是情态动词中的考点之一。mustn’t不准,禁止needn’t没必要(=don’thaveto)can’t不能;不可能maynot可能不,1/2shouldn’t不应该(=oughtnotto)可兼做行为动词的情态动词：need、dare情态动词(+动词原形)行为动词needdare1.无人称和数的变化;2.尤其用于：*否定句及疑问句中;*在if/whether之后;*或与hardly,never,noone,nobody连用;3.常以needn’t和daren’t的形式出现;4.dare有其过去时dared.多用于肯定句;(sb.)needtododaretodo(sth)needtobedone(sth.)needdoingveryuncertainalmostcertainmightshouldmustmaycouldoughttowill1.He_____beathome.2.He_____beathome,forhejustcalledmefromhishome15secondsago.A.mayB.mightC.mustA.mayB.mightC.must(can)•表示否定的猜测时can't/couldn't语气最强，指“不可能”；may/mightnot语气最弱，意思是“可能不”。•一些情态动词表猜测时的用法限制。must只用于肯定句；may/might一般不用于疑问句；could可用于各种句式；而can多用于否定句、疑问句，用于肯定句时，多指“客观可能性”。如：Lightningcanbeverydangerous.闪电可能会非常危险。can/beableto区别:Edisonalwayswonderedwhyhenscouldhatch(孵)chickenswhilehewasnotableto.Question:Arethetwomodalverbsinterchangeable(互换)?Ifnot,why?can表示与生俱来的能力或一种客观可能，而beableto更加强调通过后天的学习和努力获得的能力，或者在某个客观的场合和背景下，能做到的事情。advisabilitynecessityoughtto/shouldhavetomustYourmotherbringsyouupandtakesgoodcareofyou,sowhensheisold,you___lookafterherinreturn.A.canB.mayC.havetoD.musthaveto•1.haveto表示一种客观的需要，即周围的环境、状况等要求或迫使某人不得不做某事。•It'srainingoutside,soIhavetoputonmyraincoattogoout.2.haveto的否定式don'thaveto，相当于needn't，表示没有义务或没必要做某事，意为不必，常用于回答must引导的疑问句。MustIturninmyhomeworknow?-Yes,youmust/haveto.-No,youneedn't/don'thaveto.
