八年级下册情态动词讲解

1情态动词（一）情态动词的定义:情态动词表示说话人对某一动作或状态的态度。（二）情态动词的特点1.情态动词有一定的词义。2.情态动词不能单独做谓语，它必须和其他动词的原形一起构成谓语。3.情态动词没有人称，数的变化。（三）情态动词的结构和意义1.情态动词的基本句型肯定句：主语+情态动词+动词原形+......否定句：主语+情态动词+not+动词原形+......疑问句：情态动词+主语+动词原形+......2.情态动词的意义must“必须”；can/could“能，会”；may/might“可以”；should“应该”；would“愿，要”；haveto“不得不”；need“需要”（四）情态动词的基本用法1.can(could主要指过去时间)1）表示人或物本身所具有的能力，意为“能，能够，会”:Twoeyescanseemorethanone.两只眼比一只眼看得清。2）表示可能（理论上或是逻辑判断上）Hecan’t(couldn’t)haveenoughmoneyforanewcar.他不可能有足够的钱买新车。3）表示允许：CanIhavealookatyournewpen?我可以看一看你的新钢笔吗？Heaskedwhetherhecouldtakethebookoutofthereading-room.他问他可不可以把书带出阅览室。4）表示对现在动作或状态的猜测，主要用于否定句和疑问句中或感叹句中:Hecan’t(couldn’t)beoversixty.他不可能超过六十岁。5）could表示比can更委婉客气的提出问题或陈述看法，指的是现在时间。Can(Could)youlendmeahand?帮我一把好吗？can和beableto的用法比较(1)主语都可用来表示“有能力”，beableto强调通过努力而做到的。Adeercan/isabletorunveryfast.(2)beableto可以表示“在过去某人能够做某事且做到了”。Allthepeoplewereabletorunoutofbuildingfromthebigfire.2.may(might)1）表允许，询问或说明一件事可不可以做，might指过去时间；但在疑问句中might也可指现在时间，语气比may更委婉。May(Might)Iaskforaphotoofyourbaby?我可以要一张你宝宝的照片吗？肯定回答：may,或Yes,please./Certainly./Sure./Ofcourse.2否定回答根据说话人的语气由强到弱分：mustnot(mustn’t)（禁止）/hadbetternot（最好别）/maynot（不行）2)may表可能,但所表示的可能性不如can所表示的那样肯定。might可以指过去时间，也可以指现在时间，但语气更加不肯定。Hemaybeathome.他可能在家。Theymightbehavingameeting,butI’mnotsure.他们有可能在开会，不过我不肯定。3.must（haveto表示客观需要）1）表示“必须”（主观看法）时，用于肯定句或疑问句；用于否定句时表示“禁止”。Wemustdoeverythingstepbystep.我们一切都必须循序渐进地做。2）表示揣测。意为“想必、准是、一定”等，只用于肯定句。Hemustbeill.Helookssopale.他准是病了。他的脸色苍白。3)must的疑问句，肯定回答用must，否定回答用needn’t或don’thaveto。4.shall1）在疑问句中用于征求对方意见，主要用于第一人称(在英国英语中，也用于第三人称)，其意为“要不要”、“…好吗”：ShallIgetyouachairforyou?要不要我给你拿把椅子来?2）在陈述句表示说话者的允诺、告诫、威胁、命令、规定、必然性等，主要用于第二、三人称：Youshallsufferforthis.你会为此事吃苦头的。(表威胁)Thatdayshallcome．那一天一定会来。(表必然性)Tellhimthatheshallhavethebooktomorrow.告诉他这本书明天给他。(表允诺)【注】有时用于第一人称，表示决心：Ishallreturn.我一定回来。(表示决心)5.should1）表责任或义务，意为“应该”，用于各种人称。Youshouldbepolitetoyourteachers.你对老师应该有礼貌。2）表推测，意为“想必一定、照说应该、估计”等。Thefilmshouldbeverygoodasitisstarringfirst-classactors.这部新电影是一流演员主演的，估计拍得很好。6.will1）表意愿,用于各种人称。Iwilldoanythingforyou.我愿为你做任何事。2)will在疑问句中用于第二人称，表示询问对方的意愿或向对方提出请求Willyouclosethewindow?请你把窗户关上好吗？7.would1）will的过去式，表示过去时间的“意志、意愿”。IsaidIwoulddoanythingforyou.我说过我愿意为你做任何事。2）would用于现在时间，表示比较委婉地提出请求、建议或看法。Wouldyoulikeanotherglassofbeer?再来杯啤酒好吗？8.need1)need作为情态动词，主要用于否定句疑问句；作为实义动词可用于肯定句，否定3句或疑问句中。Youneedn’ttelephonehimnow.你现在不必打电话给他。2)回答由need引起的问句时，肯定回答一般用must，否定回答是用needn’t--NeedIcome?--Yes,youmust.--我需要来吗？--需要。情态动词练习题()1.John___cometoseeustonight,butheisn'tverysureyet.A.mayB.canC.hastoD.must()2.They___dowellintheexam.A.canbeabletoB.beabletoC.canabletoD.areableto()3.-MayItakethisbookout?-No,you___.A.can'tB.maynotC.needn'tD.aren't()4.You___goandseeadoctoratoncebecauseyou'regotafever.A.canB.mustC.dareD.would()5.-CanyouspeakJapanese?-No,I____.A.mustn'tB.can'tC.needn'tD.maynot()6.-He___beintheclassroom,Ithink.-No,he___beintheclassroom.Isawhimgohomeaminuteago.A.can;maynotB.must;maynotC.may;can'tD.may;mustn't()7.-ShallIgetonemorecakeforyou,Dad?-Thanks,butyou___,I'vehadenough.A.maynotB.mustnotC.can'tD.needn't()8.Eventhetopstudentsinourclasscan'tworkoutthisproblem,soitbeverydifficult.A.mayB.mustC.canD.need()9.Heisn'tatschool.Ithinkhe___beill.A.canB.shallC.mustD.hasto()10.___Itakethisone?A.MayB.WillC.AreD.Do()11.Thechildren___playfootballontheroad.A.can'tB.canC.mustn'tD.must()12.You___belateforschoolagainnexttime.A.mustn'tB.needn'tC.don'thavetoD.don'tneedto()13.-MustIdomyhomeworkatonce?-No,you___.A.needn'tB.mustn'tC.can'tD.maynot()14.Hisarmisallright.He___goandseethedoctor.A.hasnottoB.don'thavetoC.haven'ttoD.doesn'thaveto()15.Hehadtogiveuptheplan,___he?A.didB.didn'tC.doesD.doesn't()16.Theyhadtowalkhere,___they?A.mustn'tB.didC.didn'tD.hadn't()17.Hehadbetterstayhere,___he?4A.didn'tB.don'tC.hadn'tD.isn't()18.You'dbetter___latenexttime.A.nottobeB.notbeC.won'tbeD.don'tbe()19.You'dbetter___yourhair___onceamonth.A.had;cutB.had;cuttedC.have;cutD.have;cutted()20.You___askthatmanoverthere.Maybeheknowstheway.A.hadbetternottoB.hadnotbetterC.hadbetterD.hadbetternot()21.-ShallwegoandvisittheHistoryMuseumnextSunday?-___.A.HereyouareB.Sorry,Ican'tC.Yes,pleaseD.Letmetry()22.-Whydon'tyouaskMiketogowithus?-Thanks,___.A.IwillB.Iwon'tC.leanD.Imay()23.-___Itakethenewspaperaway?-No,youmustn't.You____readitonlyhere.A.Must;canB.May;canC.Need;mustD.Must;must()24.Excuseme.___youpleasepassmethatcup?A.DoB.ShouldC.WouldD.Must()25.___youliketohaveanothertry?A.CouldB.WillC.WouldD.Do()26.-Wouldyouliketogoboatingwithus?-Yes,___.A.I'dlikeB.IwantC.I'dliketoD.Ido()27.You___worryaboutyourson.Hewillgetwellsoon.A.needn'tB.can'tC.mustn'tD.haveto()28.Thepoormanneedsourhelp,___he?A.needB.needn'tC.doesD.doesn't()29.-Mustwedoourhomeworkfirst?-No,you___.Youmayhavearestfirst.A.mustn'tB.needn'tC.maynotD.can't()30..–Iwastoldtobeherebeforeeight.--Oh,you____.I’msorryfornottellingyouthatwehavechangedtheplan.A.mustB.can’tC.mayD.needn’t()31.You____writethepoemdown.Ourteacherwillgiveusacopy.A.can’tB.shouldn’tC.needn’tD.mustn’t()32.We____keepthenewtrafficlawandlearnhowtoprotectourselves.A.mayB.shouldC.canD.need()33.Mrs.Green____gotohos