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can和could1.can/could表示能力，只用于现在式和过去式(could)。beableto2.can表示客观可能性.Anybodycanmakemistakes.Itcanbecoldinwinterinthesouth.3.表示许可.Youmay/cancomein.4.用在否定句或疑问句中,表猜测,怀疑,惊讶Thatcan’tbeTom.HewenttoLondontwoweeksago.Thefirespreadthroughthehotelveryquicklybuteveryone____getout.(NMET97)AhadtoBwouldCwasabletoDcouldCHecouldswimacrosstheEnglishChannel.Buthedidn’tfeellikeitthatday.(能力）YesterdayIwasabletogethomebeforetheheavyrain.Beabletodosth=managetodosth=succeedindoingsth1.表示允许或请求canmay/canIhelpyou?2.没有把握的推测。Shemaycometomorrow.Shemaynot(可能不）gotothepartytonight.3.放在句首,表示祝愿。MayGodblessyou!might表示推测时,不表示时态,只是可能性比may小。Theymightbehavingameeting,butI’mnotsure.may和might---AreyoucomingtoJeff’sparty?------I’mnotsure.I___gototheconcertinstead.(NMET00)AmustBwouldCshouldDmightD---IsJohncomingbytrain?---Heshould,buthe__not.Helikesdrivinghiscar.(NMET02)AmustBcanCneedDmayDPeter___comewithustonight,butheisn'tverysureyet.A.mustB.mayC.canD.will答案B.表可能性只能用may.此句意可从后半句推出。I’msurehe___havethecomputersoonerorlater.AshallBcanCmustDwouldChaveto和must“必须”1.haveto表示由于客观因素不得不做must表示说话人的主观意志,看法1.Mybrotherwasveryill,soIhadtocallthedoctorinthemiddleofthenight.2.Hesaidthattheymustworkhard.2.haveto有人称、数、时态的变化，而must只有一种形式。Hehadtolookafterhissisteryesterday.3.否定结构中don’thaveto表示“不必”mustn’t表示“禁止”Youdon’thavetotellhimaboutit.你没必要把此事告诉他。Youmustn’ttellhimaboutit.你一定不要把这件事告诉他。4.–MustIreturnthebooktoday?-Yes,youmust.-No,youneedn’t./No,youdon’thaveto.NeedIcallheragain?---Yes,you_____.---No,you_______.mustneedn’tdon’thavetoMayIuseyourbicycle?---Yes,you_____.---No,you_______.maycan’t---MayIuseyourmotorbike?---No,you___.Acan’tBshouldn’tCneedn’tDmustn’tA–MayIleavenow?-Yes,youmay.-No,youmustn’t.Wemustgonow,______?---Mustwegonow?---Yes,you______.---No,you_________.needn’tyoumustneedn’tdon’thaveto1.will在疑问句中表示请求和建议.would比will更婉转,礼貌Willyoucometomyoffice?2.表示愿意去做某事或决心做某事.Iwillmarryyou.Ifyouwillcometotheparty,wewillbeveryhappy.作为情态动词will可以用于条件状语从句will和wouldwould和usedto1）usedto表示过去与现在或过去某时与后来的情况有不同，而would只表过去的情况(过去往往)。Peopleusedtothinkthattheearthwasflat.Shewouldgooutforawalkinthemorningwhenshewasinthecountry.2）usedto可表示过去习惯性的动作和经常的状态，would只表示过去习惯的动作。Heusedto/wouldsmokewhilewriting.Sheusedtobefat.shall1)在疑问句中shall用于一,三人称,表示征求对方的意见或指示Shallhecometoseeyou?WhatshallIdotohelpyou?2)在陈述句中shall用于二,三人称,表示告戒,警告,命令,决心,允诺等意图.Heshallgowithus.Ithinkyoushalldoit.1.ShallIcarryyourluggage?2.Shallhecometoseeyou?1.YoushalldoasIsay.2.Nobodyshallsayaword.3.Youshallfallbehindinyourexamifyoukeepplaying.1.Youshallhaveanicepresentforyourbirthday.2.HeshallhavethebookwhenIfinishedreadingit.1.---Theroomissodirty.___wecleanit?(NMET03.Beijing)A.WillB.ShallC.WouldD.DoB2.---Excuseme,butIwanttouseyourcomputertotypeareport.---You____havemycomputerifyoudon’ttakecareofit.Ashan’tBmightnotCneedn’tDshouldn’tAshould1).should(主观)和oughtto(客观)都表示劝告,建议或有责任,义务去做某事为“应该,必须”的意思，可用于各种人称。YoushoulddoasItoldyou.2).Should/oughttohavedone表示某事在过去本应该做而实际未做;shouldn’t/oughtn’thavedone本不应该做而实际却做了.(责备)Youshouldhavecomehereearlier.Youshouldn’thavebeenthere.1.Studentsshouldrespectteachers.2.Hesuggestedthatweshouldactatonce.3.Theboysshouldn’tbeplayingfootball.Theyshouldbeatschool.4.Youshouldn’thaveenteredtheteacher’sofficewithoutpermission.5.Heshouldbe20years.6.Itshouldbefinetomorrow.need和dare1)作为情态动词时，两者都主要用于疑问句、否定句和条件句。2)need作实义动词时后面的不定式必须带to，而dare作实义动词用时,后面的to时常可以被省略。---Dareyougotherealone?---Yes,I_____.---No,I_______.Youdaregotherealone,________?Youdaretogotherealone,________?daredarenotdaren’tyoudon’tyou3)need否定结构needn’t=don’thaveto没有必要,不必.4)need/needn’thavedone表示本有必要做某事，而实际未做或本没必要做，而实际却做了．We___toschoolonSundays.Aneedn’tgoingBneedn’ttogoCdon’tneedgoDneedn’tgoD情态动词＋havedonemusthavedone对过去某事的肯定猜测想必，一定，准是can’t/couldn’thavedone对过去某事的否定性猜测想必不可能，一定不may/mighthavedone对过去某事的可能性猜测可能已经should/oughttohavedone过去应该做而实际未做本应该(责备,语气较强)couldhavedone本来能做的事实际却未做到(遗憾,惋惜)情态动词+have+过去分词1.musthave+donesth对过去时间里可能发生的事情的推测，语气较强，具有肯定，谅必的意思。—Lindahasgonetowork,butherbicycleisstillhere.—Shemusthavegonebybus.2．oughttoshouldhadbetter本应该做某事，而事实上并没有做。否定句表示“本不该做某事而做了”。①Yououghtto/shouldhavebeenmorecarefulinthisexperiment.②Heoughtnottohavethrowntheoldclothesaway.③Youhadbetterhavecomeearlier.havedonesth3.needn'thavedonesth本没必要做某事Idressedverywarmlyforthetrip,butIneedn'thavedoneso.Theweatherwashot.1.___he___afamousdoctoratthattime?Hewassoyoungthen.ACan;beBMust;beCCan;havebeenDMust;havebeenCcanhavedone\couldhavedone用于表示对过去发生的事进行猜测,can只能用于疑问句,否定句,其他情况用could.couldhavedone还课用来表示“本来能做而没做,有责怪的意思”例(1)-Wherecanshehavegone?-Shecannothavegonetothechurch.-Shecouldhavegoneswimming.(2)-Whydidn’tyoucomeback?Youcouldhavesavedher.2.MyEnglish-Chinesedictionaryhasdisappeared.Who___havetakenit?(NMET03.Shanghai)AshouldBmustCcouldDwouldC3.---Willyoustayforlunch?------Sorry,____.Mybrotheriscomingtoseeme.(NMET99)AImustn’tBIcouldn’tCIneedn’tDIwon’tB4.Iwasreallyanxiousaboutyou.You____homewithoutaword.(NMETOO)Amustn’tleaveBshouldn’thaveleftCcouldn’thaveleftDneedn’tleaveB5.---IstayedatahotelinNewYork.---Oh,didyou?You___withBarbara.(NMET98)AcouldhavestayedBcouldstayCwouldstayDmusthavestayedA6.Thelig