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例①HadIknownaboutthiscomputerprogram,ahugeamountoftimeandenergy______.A.wouldhavebeensavedB.hadbeensavedC.willbesavedD.wassavedA第11讲情态动词和虚拟语气［解析］本题考查虚拟语气。根据句子的倒装特征判断此处是省略了if的虚拟语气，原形是：IfIhadknownaboutthiscomputerprogram，可见条件与过去事实相反。句意为：如果我早知道这个电脑程序，就可以节省大量的时间和精力了。例②Georgeisgoingtotalkaboutthegeographyofhiscountry,butI'dratherhe______moreonitsculture.A.focusB.focusedC.wouldfocusD.hadfocused［解析］wouldrather后应用虚拟语气，表示与现在事实相反，用动词的过去式。B例③—Sorry,ProfessorSmith.Ididn'tfinishtheassignmentyesterday.—Oh,you______havedoneitasyesterdaywasthedeadline.A.mustB.mustn'tC.shouldD.shouldn't［解析］此处表示和过去事实相反的情况，应该用should+have+done：本来应该做而未做。C例④“You______haveawrongnumber，”shesaid.“There'snooneofthatnamehere.”A.needB.canC.mustD.would［解析］情态动词如果表示非常肯定的推测，用must。C例⑤—Ihaven'tgotthereferencebookyet,butI'llhaveatestonthesubjectnextmonth.—Don'tworry.You______haveitbyFriday.A.couldB.shallC.mustD.may［解析］shall在第二人称中表示允诺，还可以表示强制、命令、威胁、警告。还可以是在法律条文中的要求或规定。Bcan/must/may/should这四个情态动词可以用于推测；可以是对现在的状态、现在正在进行的动作、过去已经发生的动作或对将来发生的动作进行推测。情态动词的猜测用法情态动词(1)can't…too/over=can't…adj./adv.enough再……也不过分Aparentcan'tbeover/toopatient.Wecan'tdrivecarefullyenough.(2)can'thelp/choosebutdo…不得不做……Shecan'thelpbutdropschool.(3)can'thelp(to)do不能帮忙做(4)can'thelpdoing情不自禁做(5)can't/couldn'tagreemore十分赞成(6)itcan't/couldn'tbebetter十分好，非常好can的一些特殊搭配情态动词情态动词的完成式：表示动作发生在过去，但带有“虚拟语气”的意义。(1)couldhavedone本来能够做而实际上未做(2)mighthavedone本来可以做而实际上未做(3)should/oughttohavedone本来应该做而实际上未做。(4)oughtnottohavedone/shouldn'thavedone本来不应该做而实际上做了(5)needn'thavedone本来不必要做而实际上做了情态动词的完成式情态动词if的三种虚拟形式虚拟语气主句从句与现在事实相反would/could/should/mightdodid与过去事实相反should/would/could/mighthavedonehaddone与将来事实相反would/should/could/mightdowereto+动词原形should+动词原形did(1)名词性从句中，当谓语动词表示“建议，命令，要求”等意义时，名词性从句用(should)+动词原形。(2)Iwish(that)+宾语从句(从句必须使用虚拟语气)(3)wouldrather/prefer+that从句(从句用虚拟语气)①表示愿望与现在事实相反，从句用一般过去时；②表示愿望与过去事实相反，从句用过去完成时。名词性从句中的虚拟语气情态动词(4)名词性从句表示说话人“强烈”的感情色彩，此时，从句用should+动词原形/should+havedone(表示动作在过去已经发生)，should可译为“应该，居然，竟然”。should也可以省略。常见的句型如下：①主语+be+sorry/disappointed/surprised+that从句②Itisapity/ashame/anhonour/nowonderthat从句。名词性从句中的虚拟语气情态动词(1)ifonly要是……就好了=Iwish…(与wish后面的虚拟语气类似)例：Ifonlyyouhadn'ttoldhimthenews.(2)without/butfor如果没有……例：Humanbeingswoulddiewithoutwater.=Humanbeingswoulddieiftherewerenowater.Icouldn'thavesucceededbutforyourhelp.=Icouldn'thavesucceededifyouhadn'thelpedme.含蓄虚拟语气情态动词(3)otherwise/or否则，不然的话例：Ihadnomoneythen.OtherwiseIwouldhaveboughtthatbook.=IfIhadhadmoneythen,Iwouldhaveboughtthatbook.(4)含虚拟语气的句子+but+真实情况例：Iwouldhaveboughtthatbook,butIhadnomoney.含蓄虚拟语气情态动词①—Whydidn'tyoubuyit?—I______butIdidn'thavethemoney.A.wouldB.wouldhaveC.hadhadD.hadbought［解析］从Whydidn'tyoubuyit?可以判断出是过去我并没有买下它，因为我在当时并没有钱。butIdidn'thavethemoney暗含了ifIhadhadthemoney这样的假设，故而Iwouldhave则表示IwouldhaveboughtitifIhadhadthemoney.即结果与过去事实相反。B②It'sstrangethatsuchayounglady______havea10yearoldson.A.mayB.needC.shallD.should［解析］在It'sstrangethat…句型中，谓语动词用shoulddo。D③—It'sapitythatyoudidn'tcometojoinusinthecamp.—IfI______sobusy,Iwouldhave.A.weren'tB.wasn'tC.hadn'tbeenD.shouldn't［解析］与过去事实相反的虚拟。C④—Kate,willyoucometomypartytonight?—Yes,butIreally______，asIhaveanimportantappointmentwithMr.Brown.A.can'tB.won'tC.mustn'tD.shouldn't［解析］can't表示客观情况不允许，来不了了。A⑤—WhatdoyouthinkofJim?—He'susuallyaquietboy,butsometimeshe______berathernaughty.A.shouldB.wouldC.canD.will［解析］can意为“可能”，表示客观上存在的一种可能性。B