2.HowmanyyearscanamountainexistBeforeit'swashedtothesea?Yes,howmanyyearscansomepeopleexistBeforethey'reallowedtobefree?Yes,howmanytimescanamanturnhishead,Pretendinghejustdoesn'tsee?Theanswer,myfriend,isblowinginthewind,Theanswerisblowinginthewind.BlowingintheWind3.HowmanytimesmustamanlookupBeforehecanseethesky?Yes,howmanyearsmustonemanhaveBeforehecanhearpeoplecry?Yes,howmanydeathswillittaketillheknowsThattoomanypeoplehavedied?Theanswer,myfriend,isblowinginthewind,Theanswerisblowinginthewind.1HowmanyroadsmustamanwalkdownBeforeyoucallhimaman?howmanyseasmustawhitedovesailBeforeshesleepsinthesand?Yes,howmanytimesmustthecannonballsflyBeforethey'reforeverbanned?Theanswer,myfriend,isblowinginthewind,Theanswerisblowinginthewind.GrammarModalverbscancouldmaymightshallshouldmustwillwouldoughttohavetodare(daren’t)need(needn’t)usedtomodalverbs1.Howmanymodalverbsdoyouknow?只作情态动词的可情态可实义的可情态可助动词的相当于情态动词的can/could,may/might,oughtto，mustneed,dare/daredshall/should,will/wouldhaveto,usedto2.What’sthedefinitionofmodalverbs?•情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语,只能和其他动词原形构成谓语。3.Whatarethefunctionsofmodalverbs?•1.Totalkabout___________________•2.Totalkabout____________________•3.Totalkabout___________________•4.Totalkabout____________________abilityobligationcertaintypermission•5.Tomake_____________________•6.Tomake____________________•7.Tomake_____________________•8.Togive_____________________requestssuggestionsoffersadvice2.ReadPartAonpage31,andthencompletethepassage.Answers(1)can(2)dare(3)can/could(4)may/might/could(5)mustn’t/shouldn’t/can’t(6)mustn’t/shouldn’t/can’t(7)can(8)needn’t1.Talkaboutability:can,could和beableto的用法Shecan/beabletosingthesonginEnglish.Thismachinecanmakeyoufeelcomfortable.1.can,beableto都可表示“能力”Can的主语是人或物,beableto的主语是人We’llbeabletofinishtheworksoon.Ihaven’tbeenabletoseethefilm.2.can只用于现在时和过去时(could)。beableto可以用于各种时态。3.could用于表示泛指过去的能力。如：IcouldreadwhenIwasfour.4.表示特定的某一过去能力或表示成功地做了某事时，只能用was/wereableto，不能用could。He_________fleeEuropebeforethewarbrokeout.Note：wasableto2.Totalkaboutobligationoughtto/shouldhavetomust*haveto能用于各种时态,且有人称和数的变化.oughtto的否定式为oughtnotto/oughtn’tto强should&oughttoShould&oughtto含义相近，都可表“责任，义务”常可互换。区别在于，oughtto常指特殊情况下的“应当”。Should则指一般情况。•Yououghttohelphimbecauseheisintroublenow.(语气强，有命令意味。)•Youshouldhavearestafterfinishingyoursports.（一般性建议）•Yououghttocallthepolicewhenyoufindsomethingwronginyourhouse.•Heshouldtakecareofthebabiestonight.*情态动词should一般不应被认为是情态动词shall的过去式，主要用法有：1)用于第一人称疑问句中询问对方的意愿，但语气较委婉温和，如：Whatshouldwedonow?我们现在该怎么办？2)表示应该、必须，常与must换用。例如：Weshould(must)masteraforeignlanguageatleast.3)用于虚拟语气:Itissuggestedthathe(should)besentthereatonce.Itisstrangethatheshouldsayso.I‘msurprisedthatheshouldeatsolittleevery.•must表主观意志，而haveto表由于客观因素不得不做完成的事情。•Must没有过去式，除在间接引语中可表示过去的时间。在直接引语中表示过去的时间用hadto代替。•Itoldherthatshemustgiveupsmoking.比较must&havetoIt’sgettinglate.Ihavetoleavenow.（客观需要）3.Totalkaboutuncertaintymigh...
