英语语法情态动词讲解及练习

情态动词概说：情态动词表示说话人的语气和情态，需要，可能，愿意和怀疑等。情态动词有一定的词义，但不完整，必须和主要动词的原形一起构成谓语。常用的情态动词有：can,could,may,might,must,haveto,oughtto,need,dare,shall,will,should,would,beableto,etc.一.can,could,beabletoI.1)can表示体力或脑力方面的能力，或根据客观条件能够做某事的能力。Ablindmancannotjudgecolor.Hecanspeakfivelanguages.2)表示许可，在疑问句中表示要求，否定句中表示不许。Can(May)Icomein?-----CanIuseyourdictionary?-----Ofcourse,youcan.Thiskindofthingcan’tgoon.3)表示可能性，常用于疑问句和否定句中，指“某事是否是事实”。Canitbetrue?Canthehallseatathousandpeople?Someoneisknockingatthedoor.Whocanitbe?Shecan’tbehere.Hecan’tbeserious.Marycan’thavegonetherealone.4)表示温和的命令或批评Youcangoandfetchsomewater.Youcancleanthewindowsfirst.Youcouldreadmoreinfuture.Youcouldbemorecareful.5)beableto与can的比较A)表示能力时可通用Noonecan/isabletodoit.Canyoucometonight?/Willyoubeabletocometonight?B)beableto可用于任何时态，can只能用在现在时或过去时（could）中。I’msorryIhaven’tbeenabletoansweryourletter.Hesays/saidhewill/wouldbeabletocomehomeforChristmas.C)表示经过努而成功地办到了某个具体的事情时，只能用beableto不可用can。Withthehelpofthefiremen,theywereabletoleavetheburninghouse.Afteryearsofhardworkhewasabletowintheprize2.could1)could是can的过去时，除具有can的各种功能外，还可以用来比较委婉，客气地提出问题或陈述看法。Couldyoucomealittleearlier?I’msorryIcouldn’tlendyouthebooknow.---CouldIborrowyourbicycle?---Yes,ofcourse,youcan.(不可用could)Icouldcomeearlier,ifnecessary.2)can和could还可表示某人或某物一时的特点，可译为“有可能，有时会”。Hecanbeveryfriendly.Hecouldbeveryproud.Mancanbeascruelaswildbeasts.Childrencouldbeverytrying.(伤脑筋)二.may,might1）表示许可，允许，译为“可以”（正式场合）Youmaytakethebookhome.Peoplemaynotpickflowersinthepark.I’dliketoaskaquestionifImayask.---MayIwatchTVtonight?---Yes,youmay.(No,youmustn’t/you’dbetternot.)---MayIsmokehere?---Yes,please./pleasedon’t.2)表示推测，“或许，可能”表示一件事或许会发生，一般用在陈述句中。Itmayraintomorrow.Theymaynotbetheretoday.Foolsmayaskquestionsmorethanwisemencananswer.Anybodymaygetill.注：may指事实上的可能性,can指逻辑上的可能性Mr.Smithlookspale.Hemaybeill.Mr.Smithisinpoorhealth.Hecanbeillatanytime.3)表示祝愿Mayourfriendshiplivelong!Mayyousucceed!Mayyouhaveagoodtime!Mayyoubehappy!4)常用在目的状语从句或让步状语从句中Getupearlysothatwemaycatchthefirstbus.Shewentbyairthatshemight/couldarriveearlier.Whoeverhemaybe,heshouldobeytherules.Hewouldworkhard,howeverrichhemightbe.5）maywell+动词原形意为“理应，有足够的理由”may/mightaswell+动词原形用来建议或劝说某人采取某种行动，有时相当于hadbetter常译为“还不如,不妨”。Hemaywellbeproudofhisson.（他大可以他的儿子为荣）Shemaywellsayso.（她说得对）Itisverylate,soyoumay/mightaswellgotobed.Might:might是may的过去式，在表示可能时可以换用，但might可能性较小，或表示更婉转的语气。Jimmaylendyoumoney.Jimmightlendyoumoney.MightIaskaquestion?MightIaskforaphotoofyourbaby?IwonderifImightborrowsomemoney?三.must,haveto,need1.must的用法：1）表示必须要做的事，意为“必须”，否定式表示不应该，不许可禁止等。在回答must的问句时,不用mustn’t,而用needn’t或don’thavetoImustleaveat9.Wemustdoeverythingstepbystep.Wemustn’twasteourtime.IfeltImustcallandseehim.---Mustwehandinourexercisestoday?---Yes,youmust./No,youneedn’t./No,youdon’thaveto.2)must表示“偏要，偏偏”，或“（干吗）硬要（多指不愉快的事）Whymustyoualwaysinterruptme?Mustyougososoon?Thecarmustbreakdownjustwhenwewereabouttostartoff.AfterIgiveheradvice,shemustgoanddotheopposite..3)must也可表示客观必然性，意为“必然会，总是会”。Allmenmustdie.Truthmustbeout.Wintermustbefollowedbyspring3)must还可表示一种推断和揣测。must+do对现在事实的猜测;must+havedone对过去事实的猜测.ThismustbeJim’spen.Youmustbejoking.Ican’tfindmykey.Imusthaveleftitinthebus.Thebookmusthavebeenwrittenbyawoman.Youmusthavebeenthinkingofsomething.2.must与haveto的比较：1).haveto比较强调客观需要，表示因客观环境或事态促使而不得不做某事；must强调主观看法，表示主观上认为有必要做某事。Imustlearnanotherforeignlanguage.Youhavetolearnanotherforeignlanguageifyouwanttoworkhere.Youmustbebackbefore10o’clock.Youhavetobebackbefore10o’clockbecausethetrainistoleaveat10:15.2)haveto多表示义务或习惯动作；must则表示一种重要或急迫的事情。Youhavetocarefortheyoung.Shehastobeattheofficebeforeeighteveryday.Youmustgotothemanageratonce,oryou’llbedismissed.3）haveto可用于不同时态，可同其他情态动词连用，而must则只有一种形式.WewillhavetobuyanotherTVset.Sheisalwayshavingtomakedecisions.Hehashadtoreconsiderhisposition.Shemayhavetostaytherelonger.Ihaveto/mustleavenow.3.need的用法：1）作情态动词用时，多用于疑问或否定句中。回答need提出的问句时，肯定常用must否定常用needn’t/don’thavetoYouneednotdoanythinghere.Heneverneedknow.Sheneedhardlysayanythingtohim.Idon’tthinkheneedcome.NeedIrepeatit?Thereneedbenohurry,needthere?---NeedIgososoon?---Yes,youmust./No,youneedn’t./No,youdon’thaveto.2)need作情态动词用时，也常用在if，或unless引导的条件状语从句或wonder后面的宾语从句。IfIneedstartearly,Iwill.IwonderwhetherIneedadvisehim.Iwon’twritetoherunlessIneedwritetoher.3）needhave+过去分词，表示不必做谋事，但却做了,有责备之意;didn’tneed/havetodo表示不必做且没做Youneedn’thavetoldthemaboutit.Iinvitedonlytwoguests,soyouneedn’thavebroughtsomuchfood.Ididn’thaveto/didn’tneedtogetupearlyonSunday,soIstayedinbeduntil8o’clock.need用做行为动词时的用法：1)needtodo;needdoing;needtobedone的用法Ineedtobuyanewdictionary.Mybikeneedstoberepaired/repairing.2)在will或shall表示的将来时中need常用做行为动词。Youwillneverneedtoworryabouthim.Youwillneedtosaynothing四.will和would的用法：1.表示意愿意志和决心或固执，用于非人主语时，表示固有性质，倾向Shewon’tlendmethemoney.Heisthemanwhowillgohisownway.I’llneverplayajokeonhim.Iwon’targuewithyou.Thewindowwon’topen.Thedoorwon’tshut.2.表示客观事实Fishwilldieoutofwater.Oilwillfloatonwater.3.表示一种揣想，用于二，三人称ItwillbeMr.Wan