人教新课标必修三 Unit 2 Healthy eating情态动词讲解

Unit1Festivalsaroundtheworld•Grammar情态动词（ModalVerbs)情态动词表示说话人对某一动作或状态的态度，认为“可能”、“应当”、“必要”等等。但本身词义不完全，不能单独作谓语动词，必须和不带to的不定式（即动词原形）连用。情态动词没有人称和书的变化。canandcouldmayandmightwillandwouldshallandshouldmustandcan’tcanandcouldSohecancarryheavybooks.abilityHecouldn'topenthedoorbyhimself.abilityCouldyouopenthedoor,please?requestCan/could的用法。1.意为“能够、会”，表示体力或脑力等方面的能力。2.意为“可以”表示许可，常在口语中代替may.3.意为“可能”用在肯定陈述句中表可能性，用在否定句或疑问句中表示猜测、惊讶等。4.canhavedone用于对过去动作的推测，表可能，常用于否定句和疑问句中。e.g.IcanspeakEnglish.CanIkeepthebookforafewdays?Youcan’tbeserious.（你不会是当真吧）Sheistwohourslate.Whatcanhavehappened?Can和beableto的区别1.can和could表示能力时，有时可以用beableto替换，由于只能表示现在时和一般过去时，当我们需要用现在完成时或其他时态时，就可以用beableto表示。当我们要强调过去确实使用了某种能力时，要用was(were)ableto,而不用could。wasableto表示“设法干成某事”而could只表示“具备某种能力”。e.g.Heissuchagoodswimmerthathewasabletosavetheboysfromdrowningtheotherday.Could的用法1。在过去的语境中，表示过去的能力、许可、可能。2。若不是出现在过去的语境中，它就是表达委婉口气。couldhavedone表示对过去发生事情的推测。e.g.Icouldn’tspeakEnglishtwoyearsago.Wherecouldshehavegone?mayandmightHemaybeinhisoffice.=(perhapsheisinhisoffice.)Hemightbehavinglunch.=(perhapsheishavinglunch.)mayandmight1）表示可能性（possibility）,用于对现在，过去或将来的推测，暗示不确定。might不是may的过去式，它所表示的可能性比may小，含较多的怀疑。Hemaybeverybusynow.(可能性较大)Hemightbeverybusynow.(可能性较小)mayandmight2）表示许可（permission），表示允许别人做某事，也可征求对方的许可。Hemaygonow.Wemaykeepthebookfortwoweeks.3）用于祈使句，表示祝愿。Mayyousucceed!Mayyouhaveanicetrip!may,might,can,could1.They(can/might)___________beawayfortheweekendbutI’mnotsure.2.You(may/might)__________leavenowifyouwish.3.(could/may)__________youopenthewindowabit,please?4.He(can/could)__________befromAmerica,judgingbyhisaccent.5.(may/can)___________youswim?6.Listen,please.You(maynot/mightnot)_________________speakduringthisexam.might表示猜测may表示许可could表示请求could表示猜测can表示能力maynot表示不允许may,might,can,could7.They(cannot/maynot)_______________stillbeout,thelightisoninthehouse.8.You(couldn’t/mightnot)_________________smokeonthebus.9.Withluck,tomorrow(can/could)__________beacoolerday.10.You(can/might)___________beright,butI’mgoingbacktocheckit.表示许可couldn’tcould表示猜测cannot表示猜测(不可能)might表示猜测willandwould1）表示意愿表示愿意做或主动提出做，如意志,愿望或决心Thatbaglooksheavy,I’llhelpyouwithit.(offeringtodosth)----YouknowthatbookIlentyou.CanIhaveitbackifyou’vefinishedwithit?----Ofcourse.I’llgiveittoyouthisafternoon.(agreement)Thanksforlendingmethemoney,I’llpayyoubackonFriday.(promise)willandwould2）表示习惯(habit,custom)Thisoldmanisstrange.Hewillsitforhourswithoutsayinganything.WewouldsitaroundGrandpaaftersupper,listeningtohisstories.3）表示请求（request）,用于第二人称,would比will更委婉。例如：Willyoucomethisway,please?Wouldyouopenthewindow?shallandshould1）shall的用法a.shall在疑问句中用于第一，第三人称，表示征求对方的意见。Shallweputoffthesportsmeetinguntilnextmonth?ShallTomgotherewithmetomorrow?b.shall用于第二，第三人称，表示说话人给对方的命令，警告，允诺或威胁。Youshallfailifyoudon’tworkharder.（警告）HeshallhavethebookwhenIfinishreadingit.(允诺)Heshallbepunished.(威胁)shallandshould2)should的用法a.should表示劝告、建议、命令。Youshouldgotoclassrightaway.b.should表示期待，用于表达合理推断(prediction，意为“应该”)，或明显的结果（意为“可能”）且所期待的事几乎是事实。Itisthreeo’clock,thefootballgameshouldbeginnow.Marytookdancinglessonsforyears,sosheshouldbeanexcellentdancer.1.We__________smokehere,becausetheworkeriscarryingsomepetrol.2.Itisdangerous.You__________leavetheroomimmediately.3.He___________gohikingwithfriendsatweekendswhenyoung.4.Writetomewhenyougethome.---I___________.5.--NeedIhandinmyexercisebookatonce?--Yes,you__________.6.Youhavebeenworkingallday.You__________beverytired.7.Itisalongtimesincewemetlasttime.You__________comeandseeusmoreoften.8.Whydon’tyoutryonthisdress?It_________lookniceonyou.will,would,shall,should,must:mustn’tshouldwouldwillmustmustshouldwill表示禁止,不许可表示建议,命令表示过去习惯表示意愿表示必须表示肯定猜测表示建议表示将会,一定会mustandcan’tmust用来表示“命令”、“推测”等含义。1）表示规定、指令表示规定、指令时主要指客观上的法律、条文规定，常常翻译为“应该、必须”之类意思。mustn't表示禁止Youmusthaveapassportifyouwanttogoabroad.2)表示主观的命令、禁止表示主观的命令、禁止时，主要指说话者主观的命令或强烈的劝告。Youcangooutwithyourfriendbutyoumustcomebackbefore11atnight.----MustIhandintheexercisetoday?----No,youneedn’t.。mustandcan’t3）表示猜测，语气非常肯定，近乎确定的意味，一般用于肯定句，意为肯定……。其否定为can’t，意为不可能…...。Youmustbeill.Icanseeitfromyourface.Hecan’tbeathome.Isawhimintheclassroomjustnow.mustandhaveto1.must用于一般问句中,肯定回答用must否定式用needn’t或don’thaveto，做“不必”,mustn’t表示“禁止，不允许”—MustIfinishallassignmentsatatime?—Yes,youmust.No,youneedn't.2.表示“必须”这个意思时，must和haveto稍有区别。must着重说明主观看法，haveto强调客观需要。另外，haveto能用于更多时态。Idon’tlikethisTVset.Wemustbuyanewone.Therewasnomorebus.Theyhadtowalkhome.NotsureVerysureHemightbeintheclassroom.Hemaybeintheclassroom.Hecouldbeintheclassroom.Heshouldbeintheclassroom.Hemustbeintheclassroom.情态动词的猜测用法1.---Therewerealreadyfivepeopleinthecarbuttheymanagedtotakemeaswell.---It____acomfortablejourney.()A.can'tbeB.mustn'thavebeenC.shouldn'tbeD.couldn'thavebeenD2.Thefirespreadthroughthehotelveryquicklybuteveryone___getout.()A.hadtoB.wouldC.couldD.wasabletoD3.Peter___comewithustonight,butheisn’tverysure.A.mustB.canC.mayD.willC4.---CouldIcallyoubyyourfirstname?---Yes,you____.A.willB.couldC.mayD.mightC5.Sorry,I’mlate.I___havet