情态动词讲义

,情态动词（ModalVerbs）,一.can,may,must作为情态动词的特点1.不可单独作谓语。2.情态动词后需加动词原形3.情态动词无人称和数的变化,二can,may,must的具体用法1.can/could非推测性用法能力“许可可以”Icanclimbthistree.Hecanreadbooks.CanIhelpyou?注意：CanIsmokehere?Yes,youcan.No,youcantIcanspeakEnglish,butIcouldnt3yearsago.Could表过去的能力和许可。,FathersaidIcouldswimintheriver.IcouldswimwhenIwasonlysix.Couldyouwaitafewdays?Yes,Ican.(couldyou比canyou语气更客气,婉转)Youcangonow(客观允许).=youmaygonow（主观）,Can与beabletoCan只有两种时态can,could，beableto有除进行时以外的所有时态。Can表示一贯的能力，beableto表示客观能力和通过努力可以达到的能力Icantswim.ButIamsureIwillbeabletoswimthroughmorepracticing.,Thefirespreadthroughthehotel,buteveryonewasabletogetoutWhentheboatsankhewasabletoswimtothebank.B)can/could推测性用法可能Hecantbeworkingnow.Isawhimjustnow.Canitbetrue?HecantbeMarysfather.Heistooyoung.,注意1)can/could推测性用法“可能”，can用于否定和疑问句中，不用于肯定句中,could可用于肯定句中.Youcouldberight,Isuppose.Mywifeisinhospitalourbabycouldarriveatanytime.,2).can/could表示对过去的推测是，用can/could(not)havedoneHecanthavegonetowork.ItisSunday.,WherecanTomhavegone?Shecouldhavegonetothecinema.Hecanthaveseenmeyesterday.,3).can用于肯定句，可表一时的可能性，”有时可能”,AhorseinthecentreofLondoncancostalotofmoney.,Youcanwalkthroughtheforestformileswithoutseeinganyone.,Oldnewspaperscanbeuseful.,could加完成式用于肯定句时，一般表过去可能完成而却未完成的动作。虚拟语气IcouldhavepassedmyexaminationeasilybutImadetoomanystupidmistakes.,-Theymanagedtotakemethoughtherewere5peopleinthecar.-Itcouldnthavebeenacomfortablejourney.,2.may/mightA).非推测性用法许可可以Youmayleaveatonce.Youmayhelpher.MayIcomein?Yes,youmay.No,youcantNo,youmaynot.No,youmustntNo,youdbetternot.,注意:1.MayIstayhere?在疑问句中主语只用于第一和第三人称中。2.Youmaynotcomein.你不可以来maynot不可以-Willhecometonight?-Hemaynot.可能不3MightIuseyourbook?MightItakehisidea?Yes,youmay.MightI比mayI语气更客气更礼貌。MightI的简单回答为Yes,youmay.,B).may/might推测性用法“可能”用于肯定和否定句.Hemayberight.Shemaybestayingathome.Hemaynotcometoday可能不Hemay/mightcometomorrow.C).may/mighthavedone表示对过去发生行为的推测，含有想必、也许是的意思。Hemight/mayhavestayedathomeyesterday.,注意:1.只用于肯定和否定句中,不用于疑问句中。2.might比may可能性更小Hemightgetajob-Hemaygetajob.3.Hemaynotcome.Hecantcome.maynot可能不cannot不可能,Youmay/mighthavehadtroubleindoingthat.Hemightnothavesettledthequestion,4.mighthavedone表示说话人对听话人的委婉的责备,”本可以做，而未做”（主语是第二人称）Youmighthavecalledme.,D).might/mayaswelldosth.还是好了,还是的好；不妨Imightaswellgivethesweetcourseamiss.,Thereisnothingtodo,soImayaswellgotobed.,Youmayaswellstaywhereyouare.,3.mustA)非推测性用法必须Youmustbehereintime.Mustweanswerit?Yes，youmust.No，youneednt.No,youdonthaveto.No，youdontneedto.Youmustntlendittoothers.,注意:1.must没有过去式Hesaidhemust/hadtoseethedoctor.2.mustnt表示“禁止，不允许，不许可”Youmustntspeaklikethat3.must/haveto/havegottomust主观看法haveto客观看法Youmustbehereat8oclock.Ihavetoworkheretomakemoney.Imustgonow.Ihavetogo,B)must推测性用法“一定,肯定”Hemusthavelivedhereforalongtime.Youmustbetired,arentyou?Hemusthavehadanaccident,hasnthe?Itmusthaverainedlastnight,didntit?Hemusthavegoneabroad,hasnthe?Hemusthavegoneabroadyesterday.ShemusthavestudiedEnglishbefore.注意:must表推测只能用于肯定句，can用于否定、疑问句。Hemustbeoff.Hecantbehere.,C.Must:偏偏Whymustyoudothat?AsIwassittingdowntosupper,thetelephonemustring.Whymustyoubesostubborn?(adj.顽固的,固执的),can,may,must的用法表,4.need,dare1)作情态动词Heneedntpayforit.Needyougonow?Yes,Imust.No,Ineednt.Youneedntgosoearly.Shedarentdoso.Dareyoudoit?Yes,Idare.No,Idarent.HowdareyousayImunfair.Iftheydarecome,theywillneverbeback.,Need,dare作情态动词时，只可用于否定句和疑问句，dare还可用于条件状语从句无第三人称单数形式，Need,dare后加动词原形need无过去式，dare有过去式dared否定句为neednt.darent.疑问句把need，dare提前。,Youneednthavewakenmeup;Idonthavetogotoworktoday.,neednthavedone表示过去做了某事，但没有做的必要，意为“本没必要”。,Youneednthavewaitedformeforsuchalongtime.,2)need,dare作实意动词时Doesheneedtoknowit?Shedidntneedtogo.Whodarestogo?Idontdaretoaskher.Weneedtothinkitover.Doyoudaretostayhere?Shedoesntdaretoaskme.Hedidntdare(to)move.,注意:need,dare作实意动词时need,dare可用于所有的肯定句和疑问句中有第三人称单数形式、过去式。need,dare后加带to的不定式。否定句和疑问句要使用助动词do,does,did等。,情态动词的简单回答Canyouswim?Yes,Ican.No,IcantMayIcomein?Yes,youmay.No,youcantNo,youmaynot.No,youmustnt.No,youdbetternot.,MustIgonow?Yes,Youmust.No,youneednt.No,youdonthaveto.NoyoudontneedtoNeedIdoit?yes,youmust.No,youneednt.Dareyoudoit?Yes,Idare.No,Idarent.Oughthetogo?Yes,heought(to).No,heoughtnt(to).,5.shall和should的用法,(1).Shall用于第一人称，表示征求对方的意愿。,Whatshallwedothisevening?,(2).Shall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。如：,Shallwebeginourlesson?Whenshallhebeabletoleavethehospital?,(3).Shall用于第二、第三人称，表示说话人给对方命令、警告、允诺或威胁。,Youshallfailifyoudontworkharder.（警告）HeshallhavethebookwhenIfinishreading.（允诺）Heshallbepunished.（威胁）,(4).Should表示劝告、建议、命令，其同义词是oughtto；在疑问句中，通常用should代替oughtto。,Youshouldgotoclassrightaway.ShouldIopenthewindow?,注意：Should的含义较多，用法较活，现介绍三种其特殊用法。请看下面的句子：,Ishouldthinkitwouldbebettertotryitagain.我倒是认为最好再试一试。,Youaremistaken,Ishouldsay.,Ishouldadviseyounottodothat.我倒是劝你别这样做。,ThisissomethingIshouldhavelikedtoaskyou.这是我本来想问你的。,结论：从以上例句可以看出：情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。,Should还可以用在if引导的条件从句，表示一件事听起来可能性很小，但也不是完全没有可能。相当于“万一”的意思。从句谓语由should加动词原形构成，主句谓语却不一定用虚拟语气。,Askhertoringmeupifyoushouldseeher.你万一见到她，请让她给我打个电话。,Ifyoushouldchangeyourmind,pleaseletusknow.万一你改变主意，请通知我们。ShouldI(IfIshould)befreetomorrowIwillcome.万一我明天有时间，我就来。,此外，Why(orHow)+should结构表示说话人对某事不能理解，感到意外、惊异等意思。意为“竟会”。,Whyshouldyoubesolatetoday?你今天怎么来得这么晚？,WhereisBettyliving?HowshouldIknow?IdontknowwhyyoushouldthinkthatIdidit.我真不知道你凭什么认为这件事是我干的。,注意：1“should+have+过去分词”结构一般表示义务，表示应该做到而实际上没有做到，并包含一种埋怨、责备的口气。如：,Sheshouldhavefinishedit.Ishouldhavehelpedher,butInevercould.Youshouldhavestartedearlier.,6.will和would的用法(1)表示请求、建议等，would比will委婉客气。如：,Wouldyoupassmethebook?,(3)用“willbe”和“will(would)+have+过去分词”的结构表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。如：,Thiswillbethebookyouwant.Hewillhavearrivedbynow.,(2)表示意志、愿望和决心。如：,Iwillneverdothatagain.Theyaskedifwewoulddothatagain.,Theguestswouldhavearrivedbythattime.Ithoughtyouwouldhavefinishedthisbynow.,Thewoundwouldnotheal.Duringthevacationhewouldvisitmeeveryweek.,(4)Would可表示过去反复发生的动作或某中倾向。Would表过去习惯时比usedto正式，并没有“现已无此习惯”的含义。如：,(5)表料想或猜想。如：Itwouldbeabouttenwhenhelefthome.Whatwouldshebedoingthere?Ithoughthewouldhavetoldyouallaboutit.,7.oughtto的用法(1)Oughtto表示应该。如：Yououghttotakecareofhim.,(2)表示推测。注意与must表示推测时的区别：Hemustbeathomebynow.（断定他已到家）Heoughttobehomebynow.（不十分肯定,Thisiswheretheoilmustbe.（比较直率）Thisiswheretheoiloughttobe.（比较含蓄）,“oughtto+have+过去分词”表示过去应做某事而实际未做。如：,Yououghttohaveaskedhim(butyoudidnt).这时，oughtto和should可以互相换用。注意：在美国英语中，oughtto用于否定句和疑问句时，to可以省略。,Oughtyousmokesomuch?Yououghtntsmokesomuch.,8.usedto，hadbetter，wouldrather的用法,(1)Usedto表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变。Hetoldusheusedtoplayfootballwhenhewasyoung.,疑问句Didyouusetogotothesameschoolasyourbrother?Usedyoutogotothesameschoolasyourbrother?,否定句Iusednttogothere.Ididntusetogothere.,其反意疑问句或简略回答中，也有两种形式：Sheusedtobeveryfat,didntshe?（正式）/use(d)ntshe?（口语）Didyouusetoplaych