高考英语一轮复习之情态动词知识精讲讲义

高中英语一轮复习之情态动词知识精讲一、情态动词及其否定形式情态动词表示说话人对某动作和状态的态度和意愿,有一定的词意,但不能单独作谓语必须和动词连用,没有人称和数的变化。一、can(could);may,(might);must(一)表能力允许或必须Hecanseeabirdamileaway.(现在)Shelistened,butshecouldhearnothing.(过去)Youmaycomeatanytimeyoulike.MayIcomein?Yes,youmay./No,youmustn't.May(Can)Ismokehere?Yes,youmay(can).Wemustworkhardforourmotherland.Mustyougososoon?Yes,Imust./No,Ineedn't.[注意]:1.could在陈述句中表示过去的能力。在疑问句中表示委婉地提出自己的看法或请求，与can无时间上的区别，但回答时用现在形式(原形)。类似的还有might,would等。-Could/Can/Would/Willyoushowmethatone?-Yes,Ican/will.2.在肯定的陈述句中,can,may都可表示“可能，可以”。may表示事实上的可能性，或正在发生或将要发生的具体可能性。can表示逻辑上的可能性和一般的可能性。Maryisinpoorhealth.Shecanbeill.(逻辑)Marylookspale.Shemaybeill.(事实)Awisemancanmakesuchmistakessometimes.(逻辑)Youmaymakesuchmistakesinthetest.can的否定和肯定不能同时出现在一个句中，但may可以。may一般不用于被动语态。Thethiefmayormaynotcomeagain.4.may一般不用二、三人称的疑问句，而can可用于各人称的疑问句,常可用likely或doyouthink来表达。Doyouthinkitwillrain?Isitlikelytorain?5.can与beableto①can与could表示能力时，不用beableto;beableto有更多的时态，但can可表示将来，不能用于将来。YoucancomeonSunday.②beableto的否定式一般为benotableto,而不用beunableto。Hewasnotabletojumpacross/overtheriver③beableto不能用于被动而can则行。Hecanmakeabeautifulmodelplane.Abeautifulplanecanbemadebyhim.④beableto用于过去时，表示“设法干成功了"，暗示在过去某场合经过努力才具备的能力。HecanspeakEnglishaftertwoyearsstudy.(不用beableto)Althoughthepilotwasbadlyhurthewasabletoexplainwhathadhappened.Thefirespreadthroughthehotelveryquicklybuteveryonewasabletogetout.6.疑问及其肯定与否定回答:can-can't不能;may-maynot(语气较强,少用)或mustn't(常用来表示不可以,不允许);must-needn't(不必),不用mustn't。-Willyoupleaseopenthedoor?-YesIwill./OK.-Wouldyoupleaseopenthedoor?-YesIwill./No,Iwon't.-Couldyoupleaseopenthedoor?-Yes,Ican./No,Ican't.-MayIopenthedoor?-Yes,youmay./No,youmustn't-MustIopenthedoor?-Yes,youmust./No,youneedn't.7.must,haveto①must表示“必须”时，否定needn't或don't/doesn't/didn'thaveto或haven't/hasn'hadn'tgottodbenotobligatedto;若表示过去或将来时的"必须”，到用haveto的适当形式musn1表示“禁止、不准”因为must无过去式，但must也可用于间接引语或宾语从句中表示过去。HisfatherthoughtshemusthavemetafairyHehadtogotothehospitalyesterday.Hetoldmehemustbethere.②must表示个人的意志和主观上的必要,理论上的论断和自然法则的必要;haveto表示客观上的必要。Hehastogotoschooleveryday.Hemustgotoschooleveryday.区别:Hehasn'tgottotheschool.他还没到学校。Hehasn'tgottogotoschool.他不必到学校。(二)表推测或判断may(might)通常只用于肯定或否定的陈述句中,can多用于疑问句或否定句中,must只用于肯定甸的陈述句中。may的可能性最小，must的可能性最大。Hemaybeintheoffice.MrLimay/mightbeintheteachers'office.Hecan'tbeintheroom.Isawhimoutsidejustnow.Howcanyoubesocareless?Shemustbeathome.Thelightison.[注意]:1.mustbe+v-ing表示目前情况的一种肯定推测,否定用can't。Theymustbewaitingforusatthestation.It'sshining.Itcan'tberainingoutside.2.musthave+过去分词,表示主观上对过去某事的推测,其否定用cant+have+过去分词。It'sverylate.Theymusthaveslept.It'sveryearly.Theycan'thavegonetobed.二.dare在英语中可作情态动词，也可作实义动词。1作情态动词时无人称和数的变化,有过去式,但少用;后接动词原形,主要用于否定句、疑问句和条件从句中。Hedarenot/daren’ttellhisfatherthebadnewsDareyoutouchthewire?Iftheenemydarecome,theywillnevergetaway.作实义动词时有人称和数的变化,接不定式作宾语、在疑问句和否定句中可省略toDidshedare(to)gooutatdarknight?Shedarestogothroughtheforest.当anybody,nobody作主语时,在陈述句中可省略to。Anybody/Nobodydares(to)doit.4.Idaresay...我敢说…….Idaresaytherearesomemistakes.Howdareyoudosth.表示说话人的一种愤怒。Howdareyousaythat?Howdareyouopenmyletter?三、need1.need作为情态动词时无过去式，并以同一形式用于现在和将来时中，一般仅用于否定句和疑问句中,在肯定句中要用must,haveto,oughtto,should代替。Weneedn'twakeupsoearly,needwe?Needwehandinthepapers?Idon'tthinkyouneedwearacoat.①mustn't表示否定的义务，或说话人强有力的劝告,意为“禁止,不许，不必要”。②needn't表示“不必要”,没有义务;同意某一行为可以不履行，有时仅表明某一行为是不必要的。Youmustn'ttellanyone.(=Don'ttellanyone.)Visitorsmustn'tfeedthetigers.Youneedn'tmakefivecopies.Onewilldo.Youneedn'tdrivesofast.Wehaveplentyoftime.2.作实义动词时,有人称和数的变化,意为“需要,必需”。主+谓+宾(名,代,动名词,to不定式)needdoingsth.(用主动形式表被动意义)needtobedoneWeneed(tobuy)pens.Thedeskneedsrepairing/toberepaired.Theoldmanneedstobelookedafter.四、would,usedto,willwould可指过去习惯的或反复发生的动作，不能表示过去存在的状态。usedto既可指过去反复发生的动作，也可表示过去存在的状态。will可表示现在习惯性的动作或某种倾向。Chinaisnotwhatitusedtobe.Heusedtobeathief.(不能用would)Shewould/usedtositunderthetree,thinking.Thefishwilldieoutofwater-What'sthematterwiththedoor?-Itwon'tlock.五、oughtto,should1均意为“应该,应当”,oughtto比should语气强。Yououghttovisityoursickfriendmoreoften.-Idon'tcarewhatpeoplethink.-Well,youshould.2.oughtto无过去式,当用于过去情况时,特别是在宾语从句中,仍用该形式;可用于被动语态中，表示有责任、有义务去做某事。Youarehisbrother.YououghttocareforhimHeoughttobepunished.3.shouldliketodosth.相当于wish或want,但语气更委婉。I'dliketogowithyou.I'dlikeyoutogowithme.六、情态动词+have+过去分词肯定:表示该做的事而没有做。否定:不该做的事而做了。I.should/oughtto+have+过去分词，表示过去该做的事没有做。Weshouldhavegivenyoumorehelp,butwewerebusythen.Yououghttohavethoughtofthat,butyoudidn't.2.shouldn't/oughtn'tto/needn't-have+过去分词，表示不该做的却做了,不必做的却做了Youshouldn't/oughtn'ttohavetoldhimthenews.Weneedn'thavetoldhimtogoagain.3.can't+have+过去分词，表示推测过去不可能发生的事。Theycan't/couldn'thavefinishedtheworksosoon.4.could+have+过去分词，表示过去能做的事而未做。Intheseconditionswecouldhavehelpedmorechildrenmay/might+have+过去分词，表示推测过去某事也许已经发生。Youmay/mighthavereadthearticleinthenewspaper.Hemay/mightnothaveseenthefilm.might+have+过去分词，也可说明某事过去没有实现，并含有劝告甚至责备之意。Youmighthavetoldmeearlier情态动词也可和动词的进行时构成谓语,表示“应当正在,想必正在”。Whyshouldwebesittingheredoingnothing?Thisisn'twhatIoughttobedoing.Hecan'tbeswimmingtoday.情态动词与现在完成进行时连用，表示“应当一直在,想必一直在”。Youshouldhavebeenwaitingforus.Hemay/might/must/can'thavebeenreading.九、should用于表示惊讶、忧虑惋惜、惊奇遗憾等情绪时意为“竟然会，竟然”;shouldhavedone也可表“竟然已……”Thepaintingconsideredtohavecopiedshouldhavewonthefirstprize.Itworriesmethatheshouldbesolazy.他竟如此懒，真让我担心。Youcan'timaginethatawell-behavedgentlemanshouldbesorudetoalady十、shall用于二、三人称表示“强制、命令、允诺、威胁”等。Youshallfinishtheworkbefore5o'clock.HeshallhavethebookassoonasIfinishit十一、shall用于一三人称可用于征求对方意见或请求对方给予指示。1.-ShallTomcomein.sir?-Yes,please.2.-Weneedapersonbadlytothinkupsuchanidea.-Shallthenewcomerhaveatry?/ShallIhelpyouwiththework?十情态动词的一些惯用法1.can’t/couldn't+比较级“再……不过,不可能更……"Ican'tagreemore.我完全同意。Hecouldn'thavedonebetter.他做得再好不过了。cannot...too/