一、表示对已发生的事情的推测musthavedone肯定句表示肯定推测may/mighthavedone肯定句表示可能性推测can't/couldn’thavedone否定句表示否定推测特殊疑问词+can/couldhavedone…?特殊疑问句Can/could+…havedone…?一般疑问句表示疑问推测I.情态动词+havedone的用法YoumusthaveseenthefilmTitanic.HemusthavebeentoShanghai.Hemaynothavefinishedthework.Ifwehadtakentheotherroad,wemighthavearrivedearlier.Hecan’thavebeentothattown.Whocouldhavegotthebook?Canhehavegotthebook?二、表示对过去所发生的事情的遗憾或责备“本”should/oughttohavedone本该做却没做shouldn’t/oughtnottohavedone本不该做却做了couldhavedone本有能力做却没做needn’thavedone本没必要做却做了wouldhavedone本打算做却没做=wouldlike/lovetohavedonewouldratherhavedone宁愿做却没做I.情态动词+havedone的用法1.can(1)表示可能性时,指的是理论上的可能,它通常不用来表示某事实际发生的可能性或真实性。Accidentscanhappen.Anybodycanmakemistakes.(2)表示能力,可以类似于beableto。但beableto表示成功做成某事managedtodo/succeededindoing。Withourhelp,hewasabletoescapefromthefire.(暗示结果成功)II.情态动词难点透视1.can(3)习惯用法:cannot……too……“再……也不过分”、“越…越好”Youcannotbetoocarefulinthechoiceofyourfriends.(4)表示请求和允许。-----CanIgonow?-----Yes,youcan./No,youcan’t.在疑问句中还可用could,might,may代替,只是语气更委婉。II.情态动词难点透视1.can(5)表示推测惊讶、怀疑、不相信的态度,用于疑问句、否定句和感叹句中。Canthisbetrue?Thiscan’tbedonebyhim.Howcanthisbetrue?(6)习惯用法:cannotbutdosth.=havenochoicebuttodo“不得不,只好”Icannotbutchoosetostayathomebecauseoftheheavyrain.II.情态动词难点透视2.shall(1)用于第一,第三人称疑问句中,表示说话人征求对方的意见或向对方请示。Shallwebeginourlesson?Whenshallwebeabletoleavethehospital?(2)用于第二、三人称,表示说话人给对方的命令、警告、允诺或威胁。Youshallfailifyoudon’tworkhard.(警告)HeshallhavethebookwhenIfinishit.(允诺)Heshallbepunished.(威胁)II.情态动词难点透视3.should(1)表示“应该”,等于oughtto。表示义务或责任。Ishouldhelpherbecausesheisintrouble.Yououghttotakecareofthebaby.(2)表示说话人感到意外,赞叹,愤怒,惊异等感情,翻译“竟然”、“居然”。Youcan’timaginethegentlemanshouldbeathief.ItisstrangethatyoushouldthinkIdidit.II.情态动词难点透视3.should(3)表示对未发生的事情,做出主观的推测,翻译“估计”、“按道理应该”。Heoughtto/shouldbehomeatnight.Theyshouldfinishitbynow.II.情态动词难点透视4.would表示过去的习惯性动作或某种倾向。WhenIwasyoung,IwouldplaybasketballonSundays.would与usedto的区别would过去常常,现在不知道如何usedto过去常常,现在不了Heusedtobeauniversitystudent.(暗示过去是,现在不是了)II.情态动词难点透视5.may(1)用于祈使句,表示祝愿。Mayyousucceed!(2)习惯用法:may/mightaswell+do“不妨”Youmightaswellhaveananothertry.II.情态动词难点透视6.must表示必须。Youmustcomeontime.在回答引出的问句时,如果是否定的,不能用mustn’t(禁止,不准),而用needn’t,don’thaveto(不必)。----Mustwehandinourexercisebookstoday?----Yes,youmust.----No,youdon’thaveto/youneedn’t.mustn’t表示禁止。Youmustn’tplaywithmatchnexttime.禁止II.情态动词难点透视7.need(1)作情态动词sthneeddoing=sthneedtobedone.Thewashingmachineneedsrepairing.=Thewashingmachineneedstoberepaired.(2)作实义动词,有人称、时态和数的变化。后面只能接带to的不定式。Heneedstofinishhishomeworktoday.Youdidn’tneedtofinishhishomeworklastnight.II.情态动词难点透视8.will(1)表示意志、愿望和决心。Iwillneverdothatagain.Theyaskedhimifhewouldgoabroad.(2)表示请求、建议等,would更委婉。Will/Wouldyoupassmetheball,please?(3)表示对过去的动作做出估计和猜想。Itwouldbeaboutteno’clockwhenshelefthome.II.情态动词难点透视