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1、情态动词情态动词表示推测不表示推测cancouldmaymightshallshouldmustwillwouldoughttohavetodare(daren’t)need(needn’t)usedto情态动词有一定的意义,但没有人称和数的变化,不能独立使用,它和后面的动词构成谓语.只作情态动词的can/could,may/might,oughtto,must可情态可实义的need,dare/dared可情态可助动词的shall/should,will/would相当于情态动词的haveto,u
2、sedtomust,can/could,may/might的用法must1.must表示推测时,只能用于肯定句。e.g.这个电脑肯定出了问题。Theremustbesomethingwrongwiththecomputer.你努力学了一整天,一定累了吧Youhaveworkedhardallday.Youmustbetired.must,can/could,may/might的用法注意:must用于肯定句中可表示“偏偏”。Naturally,afterItoldherwhattodo,mydaug
3、htermustgoanddotheopposite.自然地,在我交代女儿做什么之后,她偏偏要做相反的事情.2.must+bedoing/do表示对现在的动作进行肯定推测e.g.他现在一定在看小说.Hemustbereadingnovelsnow.他们买了一辆新车。他们一定很有钱.Theyhaveboughtanewcar.Theymusthavealotofmoney.3.must+havedone表示对过去发生的事情作出的肯定判断e.g.他们在玩篮球,他们一定完成了作业。Theyareplay
4、ingbasketball,theymusthavefinishedtheirhomework.路是湿的。昨天晚上一定下雨了。Theroadiswet.Itmusthaverainedlastnight.对现在或将来情况推测:must+动词原形。must只能用于肯定。否定和疑问分别用can’t和can。e.g.Hemusttellalie.Canhetellalie?Hecan’ttellalie.*must-should/oughtto–may-might/could+do可能性依次减弱(对过去
5、情况推测:mustmay,might)+完成时。e.g.Youmusthavemethimbefore.must—may—might可能性依次减弱must只能用于肯定句,译成“一定”。否定和疑问分别用can’t/couldn’t和can/could。e.g.Could/Canithavehappenedlastnight?Itcouldn’t/can’thavehappenedlastnight.Hemustbereading,isn’the?Youmustdoityourself,don’tyo
6、u?Hemusthavegoneoverthearticle,hasn’the?Itmusthaverainedlastnight,didn’tit?表猜测语气的反意疑问句的构成can,could和beableto的用法e.g.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can,could和beableto
7、的用法e.g.We’llbeabletofinishtheworksoon.Ihaven’tbeenabletoseethefilm.2.can只用于现在时和过去时(could)。be able to可以用于各种时态。could用于表示泛指过去的能力。e.g.I could read when I was four.Althoughthesoldierwasbadlywounded,hewasabletotellwhathadhappened.3.表示特定的某一过去能力或表示成功地做了某事时,只能
8、用was/were able to, 不能用could。e.g.Hewas able toescapefrom Europe beforethe war broke out.Hewas able toswim before he got tired.表示过去的能力can/could1.can/could表示推测时,只能用在否定句或疑问句中。e.g.It’ssolate.CanTombereading?CanitbeMr.Green?这个人不可能是玛丽,她生病了。Itcan’tbeM