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情态动词1.情态动词的推测表达2.情态动词表达虚拟语气3.某些情态动词的特殊用法一、知识重点与难点总结知识重点：情态动词在表达推测意义的句子中的运用：（一）用情态动词表达事实的推测。can，could，might，may，must可以用来表达对事实的推测。根据说话人对事实的把握性大小，must表示“肯定…”，may/might/can/could表示“可能……”，must只用于肯定句中，may/might的否定式maynot/mightnot表示“可能不……”,而can/could可以用于疑问句，表示“可能，可能……吗?”，其否定式can’t/couldn’t表示“不可能”。用情态动词可以对现在或过去的事实进行推测。对不同的时间内容推测有不同的结构。（二）对现在的事实进行推测：主要结构：…must/may/might+动词原形be+名词/形容词/介词短语be+doing例句：1.YoumustbeJeanne.I’mMathildeLoisel.Weusedtoknoweachotherverywell.2.Theymustbeinbedalreadyatthistimeofthenight.3.Theteachermustbejoking.4.Fredaisn’tinclass.Shemustbesick.5.Theremustbesomethingwrong.6.Shemightbeveryclever,butshehasn’tgotmuchcommonsense.7.Hemaybearrivingthisevening.8.Hemaybetravelingaroundtheworld.9.Thekeyscan’tbeintheroom.Ihavejustsearcheditverycarefully.10.Canthenewsbetrue?（三）对过去的事实进行推测：结构：情态动词+havedone/been+名词/形容词/介词短语例句：1.Mrs.Longmansmusthavebeenaprettygirlinheryouth.2.Hecouldn’thaveseenAnnayesterday.She’sgoneabroad.3.IthinkImusthaveleftmyglassesinthelibrary.4.Hemighthaveoversleptagain.5.WherecanTomhavegone?情态动词表达虚拟语气：表达“本来…”，“不然早就…”。这是情态动词的一种虚拟语气用法。表示说话人所讲的与所发生的事实相反。表达了说话人的埋怨，后悔的语气。其结构是在一些情态动词后面加havedone结构。根据要表达的意思，有如下结构：shouldhavedone/oughttohavedone：本应该……shouldn’thavedone/oughtn’ttohavedone：本不该……couldhavedone：本来可以……needn’thavedone：本来没必要……wouldliketohavedone：本来很想……wouldrathernothavedone:本来不愿意……could/might/havedone:不然早就……例句：1.Youshouldn’thavelaughedathismistakes.2.Youcouldhavetoldusearlier.3.Ioughttohaveboughtthatdictionarylastweek.4.Yououghtnottohavespentsomuchtimeinreadingnovels.5.Weneednothavebeeninatearinghurrytocatchthetrain.6.Theywouldliketohaveseenthatfilmlastfilm.7.Ifhehadgivenmehisnumber,Icouldhavetelephonedhim.8.Theymighthavebeenfrozentodeathbutfortherescueintime.知识难点：某些情态动词的特殊用法：need和dare的两种形式的用法need和dare可以用做实义动词，后面接不定式（todo）结构，在疑问句和否定句中，加助动词do/does/did/或don’t/doesn’t/didn’t。作为情态动词使用时，主要用于疑问句和否定句中。情态动词needn’t（没有必要，不必）相当于don’thaveto例句：1.Itiscold,youneedtowearsomewarmclothes.2.NeedIstayherewithyouforawhile?Thankyou,youneedn’t.3.Howdareyouspeaktoparentslikethat?注意：句型Idaresay+从句。意思是：我肯定……=I’msure或Thereisnodoubtthat+从句。例句：IdaresaythatmyunclewillgetthemoneyifIdie.will和would表示“意志”或“愿意”，would则指过去愿意做……例句：1.Hesaidthathewouldhelpus.2.Youmaytelephoneifyouwillacceptthisjob.would可以表达“过去习惯做……”类似于“usedtodo”例句：1.Whenwewerechildren,wewouldgoswimmingeverysummerinthatriver.表示请求，固定的句型：Will/Wouldyoupleasedo…?/Wouldyouliketodo…?例句：Will/Wouldyoupleasegivehimamessagewhenyouseehim?shall1.用于第一，三人称，表示“请求”；“建议”或“推荐”例句：1.Shallwestartthemeetingnow?2.ShallIwatchTVnow?3.Shallmysoncarrythecaseforyou?2.用于第二人称，表示“命令，“要求”，“许诺”例句：1.Youshalltakewhateveryoulike.2.Youshallnotgotothepartywithmeifyoumakesomuchnoiseagain.在表示推测的否定句或疑问句中，常用can/can’t/could/couldn’t表示，意思是：“可能…吗?”；“…不可能…”。而不能使用mustn’t或must等词。【典型例题】1.—Doyouthinkhewilldomeafavor?—AsfarasIknow,heisthelastonetohelpothers.He_____bepreparedtogiveyouahand,though.A.mightB.mustC.canD.should分析：本题考查情态动词推测性用法。根据heisthelastonetohelpothers.（他是最不可能帮助别人的人），既然如此，那么“帮助你”的可能性也就最小了。答案为A2.—Look,someoneiscoming.Guesswhoit____be?—Ithinkit___beTom.—Idon’tthinkit___be____.A.can;must;can;heB.may;can;must;himC.must;can;must;hisD.might;must;can;himself分析：根据备选答案。can表示推测时用于疑问句或否定句中。本题首句就应该是Guesswhocanitbe?第二句应该是IthinkitmustbeTom.（说话人十分肯定）。第三句表达了说话人对前一个人的否定。即：Idon’tthinkitcanbehim/he.（不可能是他）。答案为A3.—DoyouknowMs.Wanglikeswalkingaftersupper?—Sure.She____aroundthecampusnow.A.mustbewalkingB.mustwalkC.maywalkD.maybewalking分析：关键词Sure告诉我们说话人的口气十分肯定。根据句子语境：她此刻肯定正在校园散步呢。mustbedoing表示肯定正在做。答案为A4.—IstayedatahotelinNewYork.—Oh,didyou?You_____withBarbara.A.couldhavestayedB.couldstayC.wouldsayD.musthavestayed分析：首句说：我在纽约住在一家宾馆里。在此ahotel是泛指。所以D选项不合题意。第二句在说：你本来可以和Barbara.住在一起的。Couldhavedone表示：本来可以。答案为A5.Whydidn’tyoutellmetherewasnomeetingtoday?I_____allthewayherethroughtheheavysnow.A.needn’thavedrivenB.can’thavedrivenC.mustn’thavedrivenD.shouldn’thavedriven分析：根据句意：你为什么不告诉我今天没有会？我本来没必要冒着大雪开车跑这么多路。Needn’thavedone表示本来没必要。答案为A6.Iwasreallyanxiousaboutyou.You_____homewithoutaword.A.mustn’tleaveB.shouldn’thaveleftC.couldn’thaveleftD.needn’tleave分析：根据句意：我真的很担心你，你真不应该一句话都不说就离开家。“离开家”已经发生了。Shouldhavedone正好表达了本句的意思。答案为B7.A：AreyoucomingtoJeff’sparty?B：I’mnotsure.I_____gototheconcertinstead.A.mustB.wouldC.shouldD.might分析：根据B的回答：我不一定去，我有可能去听音乐会。Might表示推测：可能。答案为D8.A：Ipromisethatshe____getanicepresentonherbirthday.B：Willitbeabigsurprisetoher?A.shouldB.mustC.wouldD.shall分析：A说：“我答应她在生日聚会上她会得到一份生日礼物。shall表示许诺。答案为D【模拟试题】1.A：IsJohncomingbytrain?B：Heshould,buthe_____not.Helikesdrivinghiscar.A.mustB.canC.needD.may2.Mr.White_____at8:30forthemeeting,buthedidn’tshowup.A.shouldhavearrivedB.shouldarriveC.shouldhavehadarrivedD.shouldbearriving3.Sorry,I’mlate.I_____haveturnedoffthealarmandgonetosleepagain.A.mightB.shouldC.canD.will4.You_____betired—You’veonlybeenworkingforanhour.A.mustnotB.won’tC.can’tD.maynot5.—Ididn’tgotoworkyesterdayafternoonbecausemycarbrokedown.—You_____mine.Iwasn’tusingit.A.mightborrowB.couldhaveborrowedC.canhaveborrowedD.oughttoborrow6.—Amanansweredthephone.Isupposeitwasherhusband.—It_____herhusband.Hehasbeendeadforages.A.must