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情态动词的语法特征2)情态动词不能单独做谓语,后面只能接动词原形，oughtto和haveto除外，。3)情态动词没有人称,数的变化,但有些情态动词,如can、will、haveto、may等有过去式。1）情态动词表说话人的某种感情或语气，对某一动作或状态的某种态度。1)Someofuscanusethecomputernow,butwecouldn’tlastyear.2)Canshebeinthecomputercenter?3)Ithoughwhathesaidcouldnotbetrue.4)Can/CouldIuseyourdictionary?5)Couldyoulendmeahand?1.表能力,意为“能，能够”，can指现在，could指过去。3.表示“请求”“允许”(表请求时，口语中常用could代替can使语气更委婉，回答时用can)2.表示推测，意为“可能”“或许”，用于疑问句或否定句，can’t和couldn’t意为“不可能”。1.can与could4.can用于疑问句或否定句中时，表惊异、不相信等，意思是“可能、能够”。6)Howcanyoubelievesuchaliarlikehim?5.can’t/couldn’thavedone表示对过去情况的否定推测,意为“过去不可能做过某事”7)Susancan’thavewrittenareportlikethis.8)Shecan’thavegonetoschool,itisSunday.6.can/couldhavedone表对过去的推测，意为“过去可能做了某事”。couldhavedone还可以表示对过去能做而未做的事情感到惋惜，意为“本能够做某事可事实上未做”9）It’sapity.Yourclasscouldhavegotthefirstprize.10）WherecanMaryhavegone?can表示“能够”时与短语beableto同义，但can只用于一般现在时或过去时，而后者可用于各种时态。另外，can表示个人有某种能力，而beableto表示某人通过努力、克服困难做成某事，相当于succeedindoingsth.；can/beableto1.Michael____beapoliceman,forhe’smuchtooshort.A.needn’tB.can’tC.shouldD.may2.Mr.Bushisontimeforeverything.How____itbethathewaslatefortheopeningceremony?A.canB.shouldC.mayD.must3.----IstayedatahotelwhileinNewYork.----Oh,didyou?You____withBarbara.A.couldhavestayedB.couldstayC.wouldstayD.musthavestayed4.MysistermethimattheGrandTheateryesterdayafternoon,sohe____yourlecture.A.couldn’thaveattendedB.needn’thaveattendedC.mustn’thaveattendedD.shouldn’thaveattendedBAAA5.There’ssomeoneoutside.Who____itbe?A.canB.needC.mayD.must6.----IsJackondutytoday?----It____behim.It’shisturntomorrow.A.mustn’tB.won’tC.can’tD.needn’t7.Itisusuallywarminmyhometown,butit____berathercoldsometimes.A.canB.needC.dareD.must8.Thefirespreadthroughthehotelveryquickly,buteveryone_______getaway.A.wereabletoB.wouldC.wasabletoD.couldACAC2.may与might1.表示“许可”或“请求”，有“可以”的意思，口语中常用might代may,表示委婉语气。否定回答时用“mustnot”表“禁止，阻止”，不用“maynot”.“maynot”表示“可能不”。Eg:1)---MayIwatchTVaftersupper?---Yes,youmay./No,youmustn’t.2)TodayisSunday.Shemaynotinherofficenow.2.表示可能性。意为“或许，可能”might比may可能性小。Eg:1)Thegirlmightbesleepingthistimeofday.2)Theymaybeinthelibrarynow.4.may/mightaswell+动词原形“…还是…的好”“不妨干某事”Eg:Youmayaswellgoandhavealook.3.may/mighthavedone表示对过去发生过的事情的推测，意为“可能已经做过某事”Eg:Ican’tfindmysunglasses.Imay/mighthavelefttheminyouroffice.1.SorryI'mlate.I_____haveturnedoffthealarmclockandgonebacktosleepagain.A.mightB.shouldC.canD.will2.Peter_____comewithustonight,butheisn’tverysureyet.A.mustB.mayC.canD.willAB3.will与would1.用于第二人称的疑问句中，表“请求、建议”等，用would比用will委婉，客气些Eg:1)Willyoulendmeyourbook?2)Wouldyoulikeacupoftea?2.用于表示意志或意愿，意为“会，愿意”。will指现在，而would指过去。用于否定句中，表示“不会、不肯、不乐意”。Eg:1)Iwon’tdothatagain.2)Theysaidthattheywouldhelpus.3)NomatterwhatIsaid,hewon’tlistentome.3.表示习惯性动作。译作“总是、惯于”，will指现在常常，would指过去常常。Eg:1)Thismanisstrange.Hewillsitforhourswithoutsayinganything.2)Marywillkeepaskingsomesillyquestions.3)Everyevening,shewouldsitbywindow,deepinthought.4)WewouldsitaroundGrandpaaftersupper,listeningtohisstories.1.Ifyou____waithereforanother5minutes,ourmanagerwillcomeback.A.shouldB.willC.needD.must2.Whenhewasthere,he______gotothatcoffeeshopatthecornerafterworkeveryday.A.wouldB.shouldC.hadbetterD.mightBA4.should与oughtto1.oughtto比should语气更重。两者都用于表劝告、建议。意为”应该、应当”。但在疑问句中常用should。oughtto的否定式为oughtn’tto或oughtnotto。Eg:Ishouldhelpherbecausesheisintrouble.Yououghttotakecareofthebaby.ShouldIopenthewindow?Whatshouldwedonext?2.两者都可表示推测，表示很大的可能性。意为“可能、按理该…”Eg:1)It’s7o’clock,heshouldbeathome.2)Theyshouldhavearrivedbynow.3.oughtto/shouldhavedone本应该干某事可事实未干oughtn’tto/shouldn’thavedone本不该干某事可事实却干了Eg:Youshouldhaveinvitedmetothepartyyesterday.Youareright.IShouldhavethoughtofthat.Youshouldn’thaveeatenallthecakesinoneday.4.Should可以用来表示说话人的惊奇等情感，意为“竟然，居然”Eg:1)It’ssurprisingthatMaryshouldlovesuchaperson.2)It’sunbelievablethattheboyshouldsingsuchabeautifulsong.1.Youcan’timaginethatawell-behavedgentleman_____besorudetoalady.A.canB.shouldC.mayD.must2.----WhencanIcomeforthephotos?Ineedthemtomorrowafternoon.----They_____bereadyby12:00A.canB.shouldC.mightD.need3.We______lastnight,butwewenttotheconcertinstead.A.musthavestudiedB.mightstudyC.oughttohavestudiedD.wouldstudyBBc5.shall1.Shall用于第一、三人称的疑问句中，表示说话人征求对方的意见或请求。Eg:1)Shallwebeginourdiscussion?2)ShallIchangetheclothesforthechild?3)ShallTomgotherewithmetomorrow?4)Henryiswaitingoutside.Shallhecomein?2.Shall用于二、三人称的陈述句，表示说话人的允诺、警告、命令、威胁等语气。Eg:1)Youshallgetananswerfrommetomorrow.2)Heshallbepunished.3)Youshallgowithme.4)TellJerrythatheshallgetagiftifhebehaveswell.1.ChairmanZhang,manypeoplewanttoseeyou.___theywaithereoroutside?A.shallB.canC.shouldD.may2.You___usemybikeifyoucanreturnittomebeforeIleavehere.A.shouldB.shallC.needD.must3.You___bepunishedifyoubreaktherule.A.shallB.shouldC.needD.mustABAmust/haveto/need1.must用于一般问句中,肯定回答用must,否定回答用needn’t或don’thaveto，意为“不必”。mustn’t表示“禁止，不允许”—MustIfinishallhomeworkatatime?—Yes,youmust.No,youneedn't/don’thaveto.Idon’tlikethisTVset.Wemustbuyanewone.Motherwasout,soIhadtolookaftertheshop.2.表示“必须”这个意思时，must和haveto稍有区别。must着重说明主观看法，haveto强调客观需要。另外，haveto能用于更多时态。Youmustbethenewteacher.Hemustbejoking.Thereisnobodyhere.Theymus