专四语法考点详解

ModalVerbs情态动词情态动词•表示说话的语气或情态。情态动词本身有词义，但不完全，不能单独作谓语，必须和动词一起构成谓语。•情态动词没有人称和数的变化。•大多数情态动词有过去式。主要情态动词CanMayWill.MustShallNeedDareHadbetterWouldsoonerWouldassoonCouldMightWouldHavetoShouldOughttoUsedtoWouldrathermightaswell情态动词问题解析：

maybe&maybeMaybe（可能是）・・・maybe（或许）（副词）Thenewsmaybetme.Mavbethenewsistme.Shemaybewaitingforyouathome.Maybesheiswaitingforyouathome.Maynot&cannotmaynot译为“可能不”、"也许不会''而非“不可以气“不可以”为mustnot或caift（不许，不可以）。——MavIsmokehere?■一No,youmustn't,/youcan't/youcannot.Thenewsmaynotbetine.Youmustn'tmoveanyofthepapersonthedesk.Can&beabletoBeableto可以表示更多的时态。Wewillbeabletofinishtheworktomorrow.Hewasnotabletorealizehisgreatestambition.Areyouabletodesignanewcomputerprogram?Shehasnotbeenabletoworkoutthecomplexproblem.oughtto的否定土oughtto的否定式是oughtnotto,疑问句只把ought提前。Yououghttoberesponsiblefbryourself.Weoughtnottolookdownondisabledpeople.Oughtwetocountonhimforthesettlementofthedebate?MustMustdoMustbeMusthavedoneMust的反意疑问句Imustgetupatsix,?Shemustbeintheclassroomnow,?Theymusthavehadgreattroubletiyingtogetthere,?用must提问时的回答•肯定回答：must•否定回答：needn't或don't/doesn'thavetoMustIcomeasearlyas6tomorrowmornmg?Yes,voumust.7JNo,youneedn^./No,youdon'thaveto.Mustift&Needn'tMusthearriveveiyearly?No,hedoesn'thaveto/No,heneedn't.Must&havetoMust:主观上认为“必须”作某事。Haveto:受客观情况迫使而“不得不”作某事Youmustworkhardernowifyouwanttofindasatisfactoiyjobaftergraduation.Childreninremoteareashavetoquitschoolsimplybecausetheirparentscannotaffordtheireducation.Imusthelphim.(obligation,responsibility}Ihavetohelpliim.{unwillingness)Must&haveto的否定•否定must表示“禁止，不允许，一定不要”•否定doiTthaveto表示“不必，不一定非得，不一定要-We/ off-the/tvip whcuC.We/dovx/thave/to^puct:off-the/tvip,althou毋Must&haveto时态的区别Must只用于现在，而haveto则可用于不同时态。用hadto表示过去，用willhaveto表示将来。Wehadtoresorttoforceinthatcase.Wewillhavetoreconsiderthewholethingifthisplanfails.Onemusthavefaithinlife.havetohaveto的疑问句和否定句都要用助动词do/does,过去式则用didoDowehavetowaitfbrhimtostartdiimer?Doeshehavetoshowyoutheticketstoenterthecinema?DidIhavetodotheothertaskaswell?Youdoifthavetocomeinperson.Shedoesn'thavetobringherdictionaiy.Wedidn'thavetomakepreparationsforthequiz.Need&dareNeed&dare既能作实义动词，又能作情态动词。Need&dare在肯定句中，通常为实义动词，后面的不定式要带to,单数第三人称加s,有时态变化。Need&dare作情态动词时，多用于否定句和疑问句。ExamplesSheneedstoworkevenharderifshewantstosucceedinherstudy.Hedarestospeakthetmth.Doyouneedtotakeabreak?Theydidiftdaretodisobey.Needheleavesosoon?Youneedifthavedonealltheheavywork.Shedarenotgohomelateatnight.HowdareyousayIamunfair?mightaswellmightaswell译为“不妨"表示规劝。YoumightaswellwaittoseewhatIcandoforyou.Youmightaswellleavenow.Wemightaswelltiyasecondtimetoseewhat'swrongwiththeequipment.beto可视为情态动词beto的三种意义•①系表结构Mydutyisinstinctstudentsonwhatiswrongandwhatisright.•②将来'时的特殊表达法Iwastogobackhomewhenthephonecalled.•③"应当”“规定是”可视为情态动词-besupposedtoYouaretoobeytheschoolmlesandregulations.Wouldrather表意愿：Iwouldrather/soonernotgothereonmyown.表选择：Shewouldratherdiethansurrendertotheenemy.(句型Wouldratherdosth.thandosth.else)•表虚拟：wouldrathersb.did/didn'tdosth.Iwouldratheryoudidn'tdoanythingforthetimebeing.Usedto&would•情态动词usedto表“过去常常做”。往往含有“不再如此”之意。Would只能表示动作，不能表示状态。而usedto都可以。.Hewouldasktheteachersomestrangequestions.Heusedtoasktheteacher Heusedtobemuchbetteroffthanheisnow.Hewouldbemuch (wrong)MoreInformationWould侧重叙述过去，而usedto强调过去和现在的对比。Sometimesshewouldgivemesomepleasantsurprises.Mymotherusedtobehot-tempered,butnowsheisveryniild.情态动词的完成式needn'thavedone表示过去本不必做的事情Youneedifthavedoneallthecalculationbyyourself.Wehavecomputerstodothatsortofwork.Sheneedn,thaverisensoearly.Therewasnohuny.Theyneedifthavebroughtsomuchfoodwiththem.Wehadenoughforalltheguests.Musthavedone对过去事情的肯定猜测Hemusthaveworkedveiyhard,fbrhedidagoodjobillthelastexam.Theymusthavehadaquanel.Theyhadn'ttalkedwitheachotherfornearlyaweek.Theremusthavebeenablackout.Thewholestreetwasindarkness.can't/couldn^thavedone对过去事情的否定猜测（musthavedone的否定形式）Itcan^havebeenher.ShehasgonetoShanghai.Youcan'thaveseenmeinthemeetinglastweek.Iwasonabusinesstripthen.Hecan'thaveworkedhard.Ihaveseenhimplayingwithhisneighborsveiyoften.could&may/mighthavedone

表示对过去事情的可能性的推测Youmay/mighthavebeeninjuredinthecaraccident.Youmayhavebeenhurtbythewildanimal.Youmayhavereadthebook.Youmighthavebeenmorecarefill.Willhavedone表示将来完成时Bytheendofthisweek,thebuildingwillhavebeencompleted.ByMayorJune,wewillhavealreadyknownwhetherChinasucceedsinbiddingforthe2008OlympicGames.Bynextmonth,wewillhavelearnedthefirst5chapters.Would/couldhavedone表示对过去虚拟Youcould/wouldhavedonemuchbetterifvonhadfollowedtheteacher'sinstmctions.Theearthcouldhavebeenabetterplaceifwehadallknowntheimportanceofprotectingtheenviromnent.Youcouldn'thavebeensomiserablehadyoulistenedtomyadvice.Shewouldn'thavefailedtheEnglishexamifshehaddoneenoughrevisionexercises.