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1、Whatcanyouseeinthepicture?ReadIfyouwanttocrossastreet,youmustwaitforthegreenlight.Youmustn’tcrossinfrontofthetraffic.Ifthelightisyellow,youshouldwait.Ifyouarenotcareful,acarmayhityou.IfyouareintheUK,youhavetodriveontheleft.andfindoutModalVerbs情态动词情态动词情态动词,顾名思义是用来表达感情和态度的动词。表明说话人的立场和
2、口气,以及说话想达到的目的常用的情态动词有：can(could),may(might),must,haveto,need,oughtto,shall,shouldcan(could)Someofuscanusethecomputernow,butwecouldn’ttenyearsago.Can/CouldIborrowthesebooks?Thestorycannotbetrue.1）能，会：表示能力，相当于beableto(beableto适用于任何时态)。2）可以，表示许可，(may较正式，could较婉转）3）可能，表示否定推测，can’tbe不可能m
3、ay(might)1.---MayIwatchTVaftersupper?---Yes,youmay.---No,Youmaynot/can’t./You’dbetternot.No,youmustn’t.2.Ifyouarenotcareful,acarmayhityou.可以，表示许可，相当于can.(注意问句中的回答）2)可能，或许，表示推测maybe可能1.---MayIwatchTVaftersupper?---Yes,youmay.---No,Youmaynot/can’t./You’dbetternot.No,youmustn’t.mustIfy
4、ouwanttocrossastreet,youmustwaitforthegreenlight.Youmustn’tcrossinfrontofthetraffic.---MustIbehomebefore8o’clock?---Yes,youmust.---No,youneedn’t/don’thaveto.3.Theremustbesomethingwrongwithmycomputer.must:必须；mustn’t:不准，禁止回答带有must的问句时，否定式常用needn’t或don’thaveto.3)一定，表示肯定的猜测。（否定猜测用can’t）
5、havetoIfyouareintheUK,youhavetodriveontheleft.Theanimalsweeathavetospendtheirliveslivingintinyspaces.haveto不得不Ihavetobeatworkatnineo’clockeveryday.ShehastoworkonSaturdays.They’llhavetostayinahotel.DoesDickhavetogotoBeijingonbusiness?Hedidn’thavetogotherelastweek.haveto+动词原形haveto有人称
6、、数、时态的变化当主语为第三人称单数时，用hasto+动词原形变问句或否定句时，需借助助动词。nothaveto=needn’tIhavetobeatworkatnineo’clockeveryday.ShehastoworkonSaturdays.They’llhavetostayinahotel.DoesDickhavetogotoBeijingonbusiness?Hedidn’thavetogotherelastweek.Ihavetobeatworkatnineo’clockeveryday.ShehastoworkonSaturdays.They’
7、llhavetostayinahotel.DoesDickhavetogotoBeijingonbusiness?Hedidn’thavetogotherelastweek.haveto+动词原形haveto有人称、数、时态的变化当主语为第三人称单数时，用hasto+动词原形变问句或否定句时，需借助助动词。nothaveto=needn’tmust和haveto两者都表示必须must侧重于说话者的主观看法，认为有必要或有义务去做某事；haveto则重于表示外界客观需要，含有不得不或被迫之意I didn't take the raincoat with me y
8、esterday.I____wait
