高中英語語法講解：情態(tài)動詞

高中英語語法講解：情態(tài)動詞概述共有10個情態(tài)動詞：can/could,may/might,will/would,shall,should,oughtto,must；2個半情態(tài)動詞need,dare特點：（1）情態(tài)動詞后加動詞原形（即不帶to的不定式）一起構(gòu)成謂語；（2）沒有人稱和數(shù)的變化；（3）多數(shù)情態(tài)動詞有過去式，但其過去式有時并不表示時態(tài)，而只起“委婉或不確定語氣”的作用。Wouldyoudomeafavour?Shemay/mightbewateringtheflowersnow.情態(tài)動詞在句子中可發(fā)揮不同作用，如表能力，表責(zé)任與義務(wù)，表推測，表征求允許，表請求，表建議，表語氣態(tài)度等等Hecan/couldrun100metersin11seconds.Youshould/oughtto/mustworkhardtowinagoldmedal.Can/Could/May/MightIwatchtheOlympicstonight?Will/Can/Could/Wouldyouhelpmewithmytraining?Hemight/may/could/should/oughtto/will/mustwatchthefootballmatchtonight.Isuggestthatyoushouldwatchtheopeningceremony.Canthisbetrue?情態(tài)動詞+do表對一般現(xiàn)在或?qū)砬闆r的推測情態(tài)動詞+bedoing表對正在發(fā)生的事情的推測情態(tài)動詞+havedone表對過去已經(jīng)發(fā)生的事情的推測一、can/could的用法表能力（1）cando現(xiàn)在一般的能力（2）coulddo過去一般的能力（3）couldhavedone過去有能力做但沒做具體某事（4）was/wereabletodo=managedtodo/succeededindoing過去有能力做且做了具體某事。注：beableto可用于各種時態(tài)、不定式中或其他情態(tài)動詞之后IcanspeakfluentEnglishnow,butIcouldn't（不能）tenyearsago.Hecouldhavefled（flee）thecitybeforethewarbrokeout,buthestayedwithhissickwife.Youcouldhavedonetheworkbetter,butyouweretoocareless.Thefirespreadthroughthehotelquicklybuteveryonewasabletogetout.表示請求和允許。（could更委婉，但答語中須用can）--Can/CouldIuseyourcomputer?--Yes,ofcourseyoucan./No,I'mafraidyoucan't.表推測（1）can在肯定句+現(xiàn)在時中，表示理論上的可能性，對某件寬泛的事情而言，并不表示具體某事是否會發(fā)生，可譯為“有時會，理論上可能”。注：若要表示具體某事發(fā)生的可能性，要用could,may,might。Moreaccidentscanhappenonsuchrainydays.Awisemancanmakemistakes.Itcanbeashotas40°Chereinsummer.Babyarelovely,butsometimestheycanbetiresome.Petercould/may/mightcomewithustonight,butheisn'tsureyet.can/could在否定句和疑問句中，可表示某事實際發(fā)生的可能性，譯為“可能(嗎)”，“不可能”。Listen,someoneiscoming.Can/CoulditbeTom?Mywalletisnowheretobeseen.Whocan/couldhavetakenitaway?Itis10o'clockinthemorning.Tomcan't/couldn'tbesleepingnow.不可能正在做某事Thestreetsarealldry.Itcan't/couldn'thaverainedlastnight.過去不可能已經(jīng)做某事4.固定用法：cannot/never...too/enough“再怎么…也不過分，越…越好"Icanneverthankyouenough.Youcan'tbetoocareful.Youcanneverremembertoomanywords.can't+比較級“不能更...，非常...”Ican'tagreemore.Thefilmcouldn't'tbemoreboringcannotbutdosth.不得不，只好Icannotbutadmireyourbravery.can'thelpdoingsth情不自禁做；can'thelp(to)dosth不能幫忙做二、may/might的用法表示請求和允許，譯為“可以”。might更委婉，否定回答可用maynot/can't/mustn't。--May/MightIuseyourpen?--Yes,youmay./--Noyoumaynot/can't/mustn't.表推測，表具體某事實際發(fā)生的較小的可能性；否定句中may/mightnot譯為“可能不”--AreyoucomingtoJeff'sparty?--I'mnotsure.Imightgototheconcertinstead.Shemay/mightnotknowheisamillionaire.may表示祝愿或希望。MayGodblessyou!Mayyoureturninsafety！Mayweneverforgeteachother！固定搭配：maywelldosth很可能Herappearancehaschangedsomuchthatyoumaywellnotrecognizeher.may/mightaswelldosth最好Youmayaswelltellmethetruth.Wemayaswellstaywhereweare.may/mighthavedone可能已經(jīng)做了某事(表推測)Sheisn'there.Shemay/mighthavemissedthefirsttraininthemorning.Hehasn'tcome.Hemay/mightnothavefinishedthework.本來可能做，但實際沒有做(含輕微責(zé)備語氣)Youshouldnothaveclimbedthetree.Youmighthavehurtyourself.Youmighthavegivenhimmorehelp,eventhoughyouwerebusy.三、must的用法表示責(zé)任與義務(wù)，譯為“必須，一定”，否定mustn't表示“禁止，不允許”注：表示“不需要，不一定”用needn't或don'thavetoYoumustfinishthetaskwithinthreedays.Thebookiswonderful.Yousimplymustreadit.Youneedn't/don'thavetowatchthematchifyoudon'twantto.Youmustn'tsmokehere.Therearepatientsinthisroom.--Mustwehandinourexercisebookstoday?--Yes,youmust/No,youneedn't/don'thaveto.注：區(qū)別于haveto：must多表示主觀自愿，而haveto表示客觀被迫，且有時態(tài)變化。Theplayisnotinteresting.Ireallymustgonow.Tosupportmyself,IhadtoworkwhenIwasyourage.表固執(zhí)態(tài)度，與別人的意愿相違背，譯為“偏要、偏偏、非要”--Howoldareyou,madam?--Ifyoumustknow,I'mtwiceyourage.Janemustdotheoppositeofherparents.Mustyoumakesomuchnoiseatsuchalatehour?Whenwewerejustgoingtohaveavacation,oursonmusthaveafever.表推測，肯定句中，表具體某事實際發(fā)生的極大的可能性，譯為“想必，一定”；否定句中，表“不可能"用can't,不用mustn'tHemustberich.Hemustbewaitingforus.Theladycan'tbe（不可能是）only30.Shemustbe（準(zhǔn)是）over50.musthavedone表示對過去已經(jīng)發(fā)生的事情進(jìn)行推測，意為“一定已經(jīng)做了某事”。Hemusthavefinishedhisessay.Otherwise,hewouldn'tgotoseethefilm.must后面反意疑問句的用法：（竅門=Iamsurethat從句）Youhaveworkedhardallday.Youmustbetired,aren'tyou?Hemustbeworkinginhisoffice,isn'the?YoumusthavelearnedEnglishformanyyears,haven'tyou?Youmusthavestayeduplatelastnight,didn'tyou?Itmusthaverained,hasn'tit?Itmusthaverainedlastnight,didn'tit?四、shall的用法（否定shallnot=shan't）疑問句中，當(dāng)主語為第一、第三人稱時，表示征求對方意見或請求指示Shallwegooutforamealtonight?Shallhe/theycometoseeyoutomorrow?Let'smeetattheschoolgatetonight,shallwe?陳述句中，當(dāng)主語為第二、第三人稱時，表示允諾，警告，威脅，命令。Youshallhavethepresentifyouworkharder.Theyshallpayforwhattheyhavedone.Lilyshallgoandbuythetickets.在條約，法律等正式文件中，表示規(guī)定，一般主語為第三人稱。Studentsshallremainintheirseatsuntilallthepapershavebeencollected.五、will/would的用法1.疑問句中，主語為第二人稱時,表示向?qū)Ψ教岢稣埱蠡蛟儐枌Ψ降囊庠浮ill/Wouldyoupleaseopenthedoorforme?(would更委婉)Letusthinktwicebeforewehavethefinaldecision,willyou?will表示臨時決定。--Thephoneisringing.--I'llanswerit.注：區(qū)別begoingto表示經(jīng)過事先考慮好的意圖。I'mgoingtomeethimattherailwaystation.我去火車站接他.(已經(jīng)考慮計劃好)will表示意愿，決心；would表示過去的意愿—Willyoumarryme?—Yes,Iwill.Ifyouwillmarryme,Iwillloveandprotectyouforever.Iwilldomybesttohelpyou.Iwon'tdoitanymore.Ipromise.Itoldhimnottogobuthewouldn'tlistentome.Whoevercame,hewouldn'tsayaword.will表示習(xí)慣性，經(jīng)常性，意為“總是，慣于”；would表示過去常常做某事Hewillsitthereforhoursreading.Hewilltalkforhoursifyoulethim.FatherwouldreadbookstomewhenIwasachild.注：would和usedto的區(qū)別：兩者都可表示“過去常常做某事”，usedto后面可用狀態(tài)動詞或動作動詞，表示該動作現(xiàn)已停止；would后只能用動作動詞，表示該動作現(xiàn)在有可能仍在做，也有可能不做了。Iusedtosmokeheavily,butIdon'tanymore.Peopleusedtobelievethattheearthwasflat.Thefamilyusedto/wouldhaveaoutgoingeverySunday.will表示傾向性，必然性，不可避免性。Fishwilldiewithoutwater.will表示某物功能的暫時失去(will不表示將來，open不用被動)Thedoorwon'topen.Thecarwon'tstart.表推測，表具體某事實際發(fā)生的很大的可能性，僅次于must，意為“很可能，十有八九會”Ithinkhewillbeallrightnow.Ithinkhewouldaccepttheinvitation.(小于will)固定搭配wouldlike/lovetodosth想要做某事wouldlike/lovetohavedonesth很想過去做了某事但沒做wouldrather/sooner+do寧愿做某事Hewouldratherlistenthantalk.wouldratherhavedone寧愿過去做了某事wouldrathernothavedone寧愿過去沒有做某事Iwouldratherhavetakenhisadvice.Iturneddownhisinvitation,butI'drathernothavedonethat.wouldrather+從句，用虛擬語氣，時態(tài)倒退。Iwouldratherhevisitedustoday/tomorrow.Iwouldratherhehadvisitedusyesterday.六、should/oughtto的用法(否定oughtnotto=oughtn'tto)1.should/oughtto表責(zé)任與義務(wù)，或勸告與建議，譯為“應(yīng)該，應(yīng)當(dāng)”；oughtto語氣比should稍強。Ishouldgoandvisitherthisevening,andyoureallyoughttocallhimatleast.--OughtItowritetosaythankyou?--Yes,Ithinkyououghtto.should/oughtto表推測，表示按照經(jīng)驗、常規(guī)，慣例等估計較可能發(fā)生的事，不出意外會發(fā)生的事，可譯為“按理應(yīng)該”Childrenshould/oughttobeabletoreadbytheageofseven.Ifhestartedoutatnine,heshould/oughttobeherenow.It'snearlyseveno'clock.Jackshouldbehereatanymoment.在表示“要求”、“建議”、“命令”的名詞性從句中，用should虛擬語氣，should意為“應(yīng)該”,可省略。Herdoctorsuggested/recommended/requiredthatshe(should)take(take)sometimeoff.Weallagreedonhissuggestionthatsomecruelsports(should)beremoved(remove).在如下句型中，should表示“應(yīng)該”或“竟然”之意，一般不省。It'shightimethatweshouldtakesomemeasurestosolvetheproblem.It'simportant/necessary/essentialthatthepublicshouldbeawareofthedangersofdrugs.It'sstrangethattheyshouldnothavepresentedyouwithacopy.It'snaturalthatyoushouldforgetit.Itisapitythatsheshouldhavelosthismoney.Ifinditastonishingthatthereshouldbeviolencehere.在if，incase，lest(以防)引導(dǎo)的條件句中，should表示“假如，萬一”不能省略。Ifyoushouldchangeyourmind,doletmeknow.Writetomeincaseyoushouldneedmyhelp.I'llremindhimlestheshouldforgetit.should表示對某事不能理解，感到意外，惱怒，可譯為“竟會、竟然”。Idon'tknowwhyyoushouldthinkthatIstolethemoney.HowshouldIknow?我怎么會知道？should用于第一人稱時，表示說話人的一種謙遜、委婉的語氣。Ishouldthinkitwouldbebettertotryitagain.我倒是認(rèn)為最好再試一試。Youaremistaken.Ishouldsay依我看，你是搞錯了。固定表達(dá)shouldhavedone/oughttohavedone應(yīng)該已經(jīng)做某事(表按經(jīng)驗對過去推測)TheyshouldhavearrivedinBeijingbythistime.本該做某事但未做(表責(zé)備)Youshouldhavecometothemeetingearlier.shouldn'thavedone/oughtnottohavedone本不該做某事卻做了Youshouldn'thavetoldMarythesadtruth.七、半情態(tài)動詞need&dare的用法1.所謂半情態(tài)動詞，即need和dare既可做實義動詞，又可做情態(tài)動詞，符合各自的規(guī)律,但dare有過去式dared，need沒有過去式?？隙ň渲衝eed/daredosth=need/daretodosth需要/敢做某事否定句中neednotdosth=don'tneedtodosth不需要、不必做某事darenotdo=don'tdare(to)do不敢做注：肯定句中need/dare通常用作實義動詞Studentsneedn'tgotoschoolatweekends.=Studentsdon'tneedtogotoschoolatweekends.Hedarednotlookatherinthefacethen.=Hedidn'tdaretolookatherinthefacethen.--NeedIhandinthepaperbeforesupper?--Yes,youmust./No,youneedn't/don'thaveto.Noonedaredsaythattheemperorhadnothingon.need固定表達(dá)：（1）sthneeddoing=sthneedtobedone某事需要被做（need做實義動詞）（2）needhavedone本有必要做但未做（3）needn'thavedone本沒有必要做但卻做了（多此一舉）（4）didn'tneedtodo本不必做某事也的確沒做Thegardenneedswatering.=Thegardenneedstobewatered.Youneedn'thavetaken（take）ataxihere,foritwasnotfa