高中英语语法讲解与练习之情态动词

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1、精选优质文档-倾情为你奉上高中英语语法之情态动词（一）情态动词的定义：情态动词表示说话人对某一动作或状态的态度。（二）情态动词的特点：1）有一定词义；2）不受主语人称和数的变化影响；3）与主要动词的原形（或称不带to的不定式）一起构成谓语（除oughtto作固定词组看待）。情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 not。 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。情态动词属非及物动词，故没有被动语态。He could be here soon. 他很快就来。 We can

2、t carry the heavy box. 我们搬不动那箱子。 Im sorry I cant help you. 对不起，我帮不上你。 基本助动词与情态助动词最主要的区别之一是，基本助动词本身没有词义，而情态助动词则有自己的词义，能表示说话人对有关动作或状态的看法，或表示主观设想： What have you been doing since? （构成完成进行体，本身无词义） I am afraid I must be going. （一定要） You may have read some account of the matter. （或许已经） 除此之外，情态助动词还有如下词法和句法特

3、征： 1） 除ought和used以外，其他情态动词后面只能接不带to的不定式。如果我们把ought to和used to看做是固定词组的话，那么，所有情态动词无一例外地只能接不带to的不定式： We used to grow beautiful roses. I asked if he would come and repair my television set. 2） 情态助动词在限定动词词组总是位居第一： They need not have been punished so severely. 3） 情态助动词用于第三人称单数现在时的时候，没有词形变化，即其词尾无-s形式： She

4、dare not say what she thinks. 4） 情态动词没有非限定形式，即没有不定式和分词形式，也没有相应的动名词： Still, she neednt have run away. 5） 情态助动词的“时”的形式并不是时间区别的主要标志。在不少场合，情态助动词的现在时和过去时形式都可以表示现在、过去或将来时间： Would you mind very much if I ask you to do something? She told him he ought not to have done it. 6） 情态助动词之间是相互排斥的，即在一个限定动词词组中只能出现一个情

5、态助动词，但有时却可以与have和be基本助动词连用： You should have washed the wound. Well, you shouldnt be reading a novel.（三）情态动词有四类：只做情态动词：must,can(could),may(might),ought to 可做情态动词又可做实义动词：need,dare 可做情态动词又可做助动词：shall(should),will(would)具有情态动词特征：have(had,has) to,used to 情态动词表猜测（四）情态动词的基本用法1.can(could)1）表示能力，could主要指过去时间

6、。Twoeyescanseemorethanone.两只眼比一只眼看得清。Couldthegirlreadbeforeshewenttoschool?这女孩上学前能识字吗？2）表示可能（理论上或是逻辑判断上）。Thetemperaturecanfallto60,thatis60belowfreezing.气温可降至60，也就是零下60。Hecant(couldnt)haveenoughmoneyforanewcar.他不可能有足够的钱买新车。Youmustntsmokewhileyourewalkingaroundinthewood.Youcouldstartafire.在林子里走时勿吸烟，那

7、样可能会引起火灾。3）表示允许。CanIhavealookatyournewpen?我可以看一看你的新钢笔吗？Heaskedwhetherhecouldtakethebookoutofthereadingroom.他问他可不可以把书带出阅览室。4）表惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。Wherecan(could)theyhavegoneto?他们会去哪儿了呢？Hecant(couldnt)beoversixty.他不可能超过六十岁。Howcanyoubesocareless?你怎么这么粗心？5）比较委婉客气地提出问题或陈述看法。Can(Could)youlendmea

8、hand?帮我一把好吗？Imafraidwecouldntgiveyouananswertoday.恐怕我们今天不能给你答复。2.may(might)1）表允许，might可以指过去时间，也可指现在时间，语气更委婉。Youmaytakewhateveryoulike.你喜欢什么就拿什么。HetoldmethatImightsmokeintheroom.他告诉我可以在房间里抽烟。May(Might)Iaskforaphotoofyourbaby?我可以要一张你宝宝的照片吗？在回答以may引起的问句时，多避免用这个词，而用其它方式，如Yes,please./Certainly./Pleasedon

9、t./Youdbetternot./No,youmustnt.等，以免显得太严峻或不客气。2）表可能（事实上）。可以指过去时间，也可以指现在时间，但语气更加不肯定。Hemaybeathome.他可能在家。Shemaynotknowaboutit.她可能不知道这件事。Hewasafraidtheymightnotagreewithhim.他担心他们可能不同意他的意见。Theymightbehavingameeting,butImnotsure.他们有可能在开会，不过我不肯定。3.must1）表示义务。意为“必须”（主观意志）。Wemustdoeverythingstepbystep.我们一切都必

10、须循序渐进地做。Youmustnttalktoherlikethat.你不可能那样对她说话。-Mustwehandinourexercisebooksnow?我们现在就要交练习本吗？-No,youneednt./No,youdonthaveto.不必。（这种情况下，一般不用mustnt） 2）表示揣测。意为“想必、准是、一定”等，只用于肯定句。Hemustbeill.Helookssopale.他准是病了。他的脸色苍白。Sheswearingadiamondnecklace.Shemusthavealotofmoney.她戴着钻石项链，一定很有钱。4.shall1）表征询意见，用于第一、第三人

11、称疑问句。ShallIgetyousometea?我给你点茶好吗？Shalltheboywaitoutside?让那男孩在外面等吗？ Whatshallwedothisevening?我们今晚做什么？2）表说话人的意愿，有“命令、允诺、警告、决心”等意思，用于第二、第三人称陈述句。 YoushalldoasIsay.按我说的做。（命令） Youshallhavemyanswertomorrow.你明天可以得到我的答复。（允诺） Heshallbesorryforitoneday,Itellyou.有一天他会后悔的，我告诉你。（警告） Nothingshallstopusfromcarrying

12、outtheplan.什么也不能阻止我们执行这项计划。（决心） 5.will1）表意愿，用于各种人称陈述句。Iwilldoanythingforyou.我愿为你做任何事。Noneissoblindasthosewhowontsee.不愿看的人眼最瞎。 Ifyouwillreadthebook,Illlendittoyou.如果你愿意读这本书，我会把它借给你。2）表请求，用于疑问句。 Willyouclosethewindow?Itsabitcold.请你把窗户关上好吗？有点冷。 Wontyoudrinksomemorecoffee?再来一点咖啡好吗？ 3）表示某种倾向或习惯性动作。 Fishw

13、illdieoutofwater.鱼离开水就不能活。 Thedoorwontopen.这门打不开。Theboywillsittherehourafterhourlookingatthetrafficgoby. 那男孩常常坐在那里好几个钟点，看着车辆行人通过。6.should1）表义务。意为“应该”（某件事宜于做），用于各种人称。Youshouldbepolitetoyourteachers.你对老师应该有礼貌。Youshouldntwasteanytime.你不应该浪费时间。2）表推测，意为“想必一定、照说应该、估计”等。Thefilmshouldbeverygoodasitisstarrin

14、gfirstclassactors. 这部新电影是一流演员主演的，估计拍得很好。Theyshouldbehomebynow.照说他们现在应当已经到家了。7.would1）表意愿。Theywouldnotlethiminbecausehewaspoorlydressed.他们不让他进去因为他衣着破旧。IsaidIwoulddoanythingforyou.我说过我愿意为你做任何事。2）表委婉地提出请求、建议或看法。Wouldyoulikeanotherglassofbeer?再来杯啤酒好吗？Wouldyoumindcleaningthewindow?请把窗户擦一下好吗？Theywouldntha

15、veanythingagainstit.他们不会有什么反对意见。3）表过去反复发生的动作或过去的一种倾向。Everytimeshewasintrouble,shewouldgotohimforhelp.她每遇到麻烦都会向她求助。他告诉我盒子打不开了。8.oughtto1）表义务，意为“应该”（因责任、义务等该做），口气比should稍重。Youarehisfather.Yououghttotakecareofhim.你是他父亲，应当管他。Yououghtnttosmokesomuch.你不应该抽这么多烟。2）表推测，暗含很大的可能，语气较弱。HanMeioughttoknowhisteleph

16、onenumber.韩梅该知道他的电话号码。Theresafinesunset;itoughttobeafinedaytomorrow.今天有晚霞，明天应该是个好天。9.usedto表示过去的习惯动作或状态，现在不复发生或存在。疑问式和否定式有两种。Heusedtoliveinthecountryside,butnowhelivesinthecity.他过去住在乡下，现在住在城里。 Thereusedtobeabuildingatthestreetcorner,butithasbeenpulleddown.街道拐角处过去有座楼房，现在拆了。Iusednt(didntuse)tosmoke.我过

17、去不抽烟。Usedyou(Didyouuse)togotoschoolonfoot?你过去常步行去学校吗？（五）其他用法首先它是动词，而且不同于行为动词，行为动词表示的是可以通过行为来表达的动作（如写，读，跑），而情态动词只是表达的一种想法（如能，也许，敢）。用法是：情态动词+行为动词原形 例句：I can read this sentence in English. 我能用英语读这句话。 情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语, 只能和其他动词原形构成谓语。 We can be there on time tomorrow.我们明天能按时去那儿。

18、 May I have your name? 我能知道你的名字吗？ Shall we begin now?我们现在就开始吗？ You must obey the school rules.你必须遵守校规。情态动词数量不多,但用途广泛,主要有下列: can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would),have (to) ,had better. 情态动词还有一个很重要的用法，即情态动词表推测情态动词表推测的用法小结（一）情态动词表推测的三种句式 1.在肯定句中一般用m

19、ust (一定)，may（可能），might / could（也许，或许）。 （1）He must/may/might know the answer to this question? 他一定/可能/也许知道这个问题的答案。 （2）It is cold in the room. They must have turned off the heating. 屋里很冷，他们肯定把暖气关了。 2.否定句中用cant / couldnt(不可能), may not/might not(可能不)。 （1）It cant/couldnt be the headmaster. He has gone to

20、 America. 这不可能是校长，他去美国了。 （2）He may not/might not know the scientist. 他也许不认识那位科学家。 3.疑问句中用can/could (能?)。 （1）Could he have finished the task? 他可能把任务完成了吗？ （2）Can he be at home now? 他现在能在家吗？ 注：以上三种句式中情态动词的语气按程度都是依次递减的。Might, could并非may, can的过去式，而表示语气较为委婉或可能性较小。 （二）情态动词表推测的三种时态 1.对将来情况的推测，用“情态动词 + 动词原形”

21、。 （1）She must / may / might / could arrive before 5. 5:00前她一定/可能/也许到。 （2）She must/may/might/could walk miles and miles among the hills without meeting anyone. 她一定/可能/也许会在山里一连走好几英里而遇不到一个人。 2.对现在或一般情况的推测，用“情态动词 + be”，“情态动词 +be doing”或“情态动词 + 动词原形”。 （1）He must / may / might / could be listening to the

22、radio now. 他一定/可能/也许正在听收音机。 （2）He cant ( couldnt ) / may ( might ) not be at home at this time. 这个时候他不可能/可能不在家。 （3）Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ? 布什先生一向准时，这次开幕式他怎么可能迟到呢？ 3.对过去情况的推测，用“情态动词 + have +过去分词”。 （1）It must / may / might / could hav

23、e rained last night .The ground is wet. 地湿了，昨晚肯定/可能/也许下雨了。 （2）The door was locked. He can ( could ) not / may ( might ) not have been at home . 门锁着，他不可能/可能不在家。 （3）Can / Could he have gotten the book？ 难道他找到书了吗？ 注：情态动词 should /ought to表推测时，意为“想必会，理应”但与“have +过去分词”连用时，则又可构成虚拟语气意为“本应该做某事却没做”。例如： （4）Its

24、seven oclock. Jack should/ought to be here at any moment. 现在七点钟了，杰克理应随时到达。（推测） （5）She should / ought to have attended your birthday party, but she had to look after her mother in hospital. （虚拟） 她本该出席你的生日晚会的，可是她得在医院照顾她妈妈。 （6）Tom should not /ought not to have told me your secret, but he meant no harm.

25、 （虚拟） 汤姆本不该告诉我你的秘密，可是他并无恶意。（六）功能助动词(auxiliary)主要有两类：基本助动词(primary auxiliary)和情态助动词(modal auxiliary)。基本助动词有三个：do, have和be；情态助动词基本的有十四个：may, might; can, could; will, would; shall, should; must, need, dare, used to, ought to.had better 上述两类助动词的共同特征是，在协助主动词构成限定动词词组时，具有作用词的功能： 1） 构成否定式： He didnt go and n

26、either did she. The meeting might not start until 5 oclock. 2） 构成疑问式或附加疑问式： Must you leave right now? You have been learning French for 5 years, havent you? 3） 构成修辞倒装： Nowhere can he obtain any information about his sister. Hardly had he arrived when she started complaining. 4） 代替限定动词词组： A: Who can

27、solve this crossword puzzle? B: Tom can. A: Shall I write to him? B: Yes, do. 重点疑难（一）need和dare的用法need和dare既可用作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句和疑问句。用作实义动词时，可用于各种句式。1.用作情态动词-NeedIcome?-Yes,youmust.-我需要来吗？-需要。 Youneednttelephonehimnow.你现在不必打电话给他。Idontthinkyouneedworry.我想你不必发愁。Shedarenotgooutaloneatnight.她

28、晚上不敢一个人出去。HowdareyousayImunfair?你竟敢说我不公平？Notoneofthemdaredmentionthis.他们谁也不敢提这件事。 2.用作实义动词Youdontneedtodoityourself.你不必亲自做这件事。 Weneedtotellthemthenews.我们需要把这消息告诉他们。Thetableneedspainting(tobepainted.).桌子需要油漆一下。 Weshoulddaretogiveourownopinion.我们要敢于提出自己的观点。 Hedidnotdare(to)lookup.他不敢抬头看。 Idaredayhellc

29、omeagain.我想他会再来的。 （cIdaresay为固定习语）（二）情态动词后跟完成式和进行式的用法1.情态动词后跟完成式，表“应当已经”，“想必已经”，“本来可以”等意。 Ishouldhavefinishedtheworkearlier.我应当早一点完成这项工作的。Heisnthere.Hemusthavemissedthetrain.他还未到，一定是没赶上火车。 Wherecan(could)hehavegone?他能到那里去了呢？ Youmay(might)havereadaboutit.你可能在报上已经读到这件事了。Youcould(might)havebeenmorecare

30、ful.你本来可以更细心的。 Heneednthaveworriedaboutit.他本不必为此事担心。Therewasalotoffunatyesterdaysparty.Yououghttohavecome,butwhydidntyou? 昨天的聚会非常有意思。你本应该来，为何不来呢？ 2.情态动词后跟进行式，表示“想必正在”，“可能正在”，“应当正在”等意。 Itstwelveoclock.Theymustbehavinglunch.现在是十二点。他们一定正在吃饭。Theymaybediscussingthisproblem.他们可能正在论讨这个问题。Hecantbetellingthe

31、truth.他说的不可能是真话。Sheshouldntbeworkinglikethat.Shesstillsoweak.她不应当那样干，她身体仍那么虚。（三）几组词的辨异 1.can和beableto 1）情态动词can只有两种时态形式，现在式can和过去式could，而beableto有多种时态形式。Marycanplaythepiano.Shehasbeenabletoplayitsinceshewas5.玛丽会弹钢琴。她五岁起就会弹了。2）用在过去时中，could经常表示能够做某事，事实上不一定去做，而waswereableto则表示“过去做成了某事”。在否定句中两者可通用。Hecou

32、ldswimacrosstheEnglishChannel.Buthedidntfeellikeitthatday.他能游过英吉利海峡，但那天他不想游。YesterdayIwasabletogethomebeforetheheavyrain.昨天我在下大雨前赶到了家里。2.must和haveto must表示主观意志，而haveto表示由于客观因素不得不做某事。must没有过去式，除在间接引语中可用于表示过去时间，在直接引语中表示过去时间应该用hadto代替。Itoldherthatshemustgiveupsmoking.我叫她必须戒烟。 Wehadtogeteverythingreadyt

33、hatnight.我们那晚得把一切准备就绪。3.would和usedto 1）usedto表示过去与现在或过去某时与后来的情况有不同，而would只表过去的情况。Peopleusedtothinkthattheearthwasflat. 过去人们认为地球是平的。（现在人们不这么认为。） Shewouldgooutforawalkinthemorningwhenshewasinthecountry.在乡下时，她总是在早晨去散会儿步。（可能现在仍有散步的习惯。） 2）usedto可表示过去的习惯动作和经常的情况，而would只表示过去的习惯动作。 Heusedtowouldsmokewhilewr

34、iting.过去他写东西时常抽烟。 Sheusedtobefat.她过去很胖 专项练习（一）1.I_you,becauseIthoughtImustbewrong. A.darenotask B.darenottoask C.darenotasking D.daretonotask 2.There_someflowersinthegarden.A.wereusedtobe B.usedtobe C.usestobe D.usedtobehaving 3.“_Itakeitout?”“Imsorry,you_.”A.Couldcouldnt B.Mightmightnot C.Couldcan

35、D.Maycant 4.Youwerestupidtoclimbthetree.You_hurtyourself. A.may B.might C.will D.mighthave 5.You_thoseletters.Whydidntyou? A.shouldpost B.shouldhaveposted C.musthaveposted D.oughttopost. 6.Allthelightsareon,theSmiths_up. A.mustget B.isgetting C.mustbegetting D.wouldget 7.He_leadahorsetothewaterbuthe

36、_notmakeitdrink. A.willcan B.maycan C.maydares D.darecan 8.“Needwedothisjobnow?”“Yes,_.” A.youneed B.youshould C.youmust D.youcan 9._tohavelunchwithustoday? A.Doyoulikes B.Wouldyoulike C.Willyouliked D.Haveyouliked 10.Hesaidthatyou_watchTValltheeveningifyouwished. A.may B.must C.can D.might 11.IsJoh

37、ncomingbytrain?-Heshould,buthe_not.Helikesdrivinghiscar. A.must B.can C.need D.may12.Peter_comewithustonight,butheisntverysureyet.A.must B.can C.may D.will 13.Michael_beapoliceman,forhesmuchtooshort. A.neednt B.cant C.shouldnt D.wont14.Ithoughtyou_behungry,soIhavebroughtyousomecakes. A.may B.might C

38、.can D.could 15.Iwonderhowhe_thattotheteacher. A.daretosay B.daresaying C.notdaresay D.daredsay 16.Comeon!We_hurrybecausethereisntmuchtimeleft. A.may B.must C.can D.need 17.AmydidbestintheEnglishtest.She_hardlastweek. A.musthaveworking B.shouldhaveworked C.shouldwork D.mustwork 18.Thefirespreadthrou

39、ghthehotelveryquicklybuteveryone_getout. A.hadto B.would C.could D.wasableto 19.-IstayedatahotelwhileinNewYork.-Oh,didyou?You_withBarbara. A.couldhavestayed B.couldstay C.wouldstay D.musthavestayed 20.Itsnearlysevenoclock.Jack_behereatanymoment. A.must B.need C.should D.can答案：1.A2.B3.D4.D5.B6.C7.B8.

40、C9.B10.D11.D12.C13.B14.B15.D16.B17.A18.D19.A20.专项练习（二）1. Jean have kept his promise. I wonder why he changed his idea.A. mustB. shouldC. needD. would 解析：选B. “should have +过去分词” 表示“过去本来应该(但没能)做某事”；keep ones promise 意为“信守诺言”。2. Jane have come to the party, but she not find the exact time.A. could; cou

41、ldB. might; couldC. should; couldD. should; would解析：选A.“ could have+过去分词表示过去本来应该(但没能)做某事”。3. So many mistakes in your homework! You more careful.A. may beB. had toC. would beD. should have been解析：选D. “You should have been more careful”. 意为：你本来应该更细心的。4Her brother be at home now, because he was seen p

42、laying basketball in the stadium just now. A. mustntB. needntC. cantD. shouldnt 解析：选C. cant be at home 意为：不可能在家。5-I cant understand why our boss is late. -He the early bus.A. could missB. may have missed C. can have missedD. might miss解析：选B. “may have+过去分词”表示对过去动作的判断，意为：可能做了某事。 注意：can表示可能时，只能用于疑问句和反

43、问句。6. She didnt answer the phone, she _ asleep.A. may beB. must beC. should have beenD. must have been解析：选D. 表示：对过去发生的事情的肯定推测。7The little girls eyes were red. She _.A. may cryB. must cryC. must be criedD. must have been crying解析：选D. 意为：她刚才肯定一直在哭。对过去某事正发生的推测。8He_ his supper now, for the dining hall i

44、s still closed.A. cant be having B. neednt be having C. mustnt be having D. shouldnt be having解析：选A. 对现在正在发生的事情的否定推测。9I parked my bike behind the building, but now it is gone. It _ . A. may be stolen B. must be stolen C. must have been stolen D. must have stolen解析：选C. 对过去发生的事情 的肯定推测的被动式。10. _ Mr. Bl

45、ack_go to work by ferry before the bridge was built?A. Did; used to B. Use; toC. Did; use toD. Does; use to解析：选C. used to do的疑问式，可以是Used+主语+to do ?或Did +主语+use to do?11. The hotel is only a stones throw away, you _ take a bus.A. need not to B. not need to C. dont need D. need not解析：选D. 说话人认为不必要乘车, n

46、eed 为情态动词。12. I am busy now, _ my brother do it for you ?A. WillB. ShallC. MustD. May解析：选B. 在疑问句中shall 用于第三人称，也表示征求意见。13. -You neednt do it right now, need you?-Yes I am afraid I _ .A. needB. needntC. mustD. mustnt 解析：选C. Yes的意思是：不。意为：恐怕我必须现在就做。14.My English-Chinese dictionary has disappeared . Who

47、_ have taken it? (2003年上海春季高考) A. shouldB. mustC. couldD. would解析：选C. could/can have done 用于否定推测和疑问推测。15. -The room is so dirty._ we clean it?-Of course. (2003年北京春季高考)A WillB. ShallC. WouldD. Do解析：选B. shall 用在疑问句中，常用于第一，三人称， 表示征求意见或请求指示。16. If you have something important to do, you _ waste any time

48、.A. needntB. mustntC. may notD. wont解析：选B. 根据句意用mustnt 17. If you want to borrow a football after school, your student card_ here.A. has to leaveB. must leaveC. has to be leftD. must be left解析：选C. have to 表示客观需要，must表示主观需要。学生证必须放在此是客观需要。18. “ Did you scold him for his carelessness?” “Yes, but _ it”A

49、. Id rather not do B. Id rather not have done C. I shouldnt do D. Id better not do解析：选B. would rather 加完成时表示对完成了的或过去了的事情的态度。意为：当时是不情愿做的。19. “ Dont get near to it . It is too dangerous!” “_” .A. Yes, I wontB. No, I dont C. No, I cantD. No, I wont 解析：选D. A为错误的表达方式；B和C没有直接回答对方的问候。 20. He must be in the

50、 classroom, _ he?A. mustntB. cantC. isnt D.can解析：选C. 对表否定的must进行反意疑问时，要用句子的实义动词21. He_ be in the garden. He must be in the room.A. cantB. mustntC. will notD. may not解析：选A. 否定推测用cant不用mustnt22. “Do you have to leave now?” “I am very sorry, but I really_.”A. cantB. haveC. shouldD. must解析：选D. 回答have to

51、 的疑问句用must作肯定回答。23. “Lets go to the library, shall we?” “_?”A. No, I cantB. Yes, I willC. Yes , thank you D. No, wed better not解析：选D. A,B,C都 不能回答shall we, 此处D的语气比较婉转客气。24. “Can I take it away?” “ You _ better not.”A. should B. couldC. would D. had解析：选D. had better 与不带to 的不定式构成谓语，可以变成疑问句：Hadnt you be

52、tter-25. You _ have brought your camera. They all had theirs with them.A. couldntB. needntC. wouldntD. mustnt 解析：选B. 本来不必要做某事.26. See who is there!_it be May?A. MayB. MustC. CanD. Will解析：选C. 表推测时A，B都用作疑问句。27. John_ be a basketball player. He is much too short.A. mayB. mustntC. cantD. should 解析：选C. 断

53、然的不定推测用cant 28. The Chinese teacher looks so pale. She _ be ill.A. mustB. mustntC. canD. need解析：选A. 表示有把握的肯定推测用must29. Something_to save our earth. Do you think so?A. can doB. must doC. has to doD. must be done解析：选D. “something must be done” 意为：必须采取措施。30. Look at what you have done! You _ be more ca

54、reful.A. oughtB. canC. wouldD. should解析：选D. ought 后应用to专项练习（三）1. Has Li Lin started? He said he would join in the party. He _. He is a man of keeping his word.A. could have left B. must have left C. cant come D. wont be coming2. May I park my car here? No, you _. No car is allowed to park here.A. ma

55、y not B. neednt C. mustnt D. darent3. Excuse me, could you tell me where the Yajia Supermarket is? Its two blocks straight ahead. You _ miss it.A. mustnt B. cant C. neednt D. shouldnt4. I saw Mr. Sun at Tongyu Station this morning. You _. Hes still on holiday in Hawaii.A. couldnt have B. mustnt have C. shouldnt D. neednt5. How about paying a visit to Dr. Wang, our former Chinese teach