八年级英语下册 语法之情态动词讲解与练习（无答案） 人教新目标版

情态动词情态动词：表示说话人语气的单词。不能单独做谓语，只能和动词原形（有时候也说不加to的动词不定式）一起构成谓语。1、情态动词没有人称和数的变化，情态动词后面跟的动词须用原形，否定式构成是在情态动词后面加 not。eg: She can sing an English song. We should do our homework right now. I cant speak English very well.2、 情态动词的用法（1）Can的用法表示体力或脑力方面的“能力”Can you drive?你会开车吗？Can you speak English?你会说英语吗？ 表示客观条件允许You can skate on the lake.(The ice is thick enough.)你可以在湖面上滑冰了（冰层够厚的了）The airplane can take off now.(The storm has stopped.)飞机可以起飞了（暴风雨停了） You cant park your car here. 你不能在此停车例1：Theworkistoohardforhim.He_finishitontime.A.cantB.mustntC.shouldntD.needntcan用在否定句和疑问句中时，有时表示说话人的怀疑，惊异、猜测或不肯定：no, no, it cant be true.不，不，这不可能是事实How can you be so careless!你怎么会这么粗心He cant be in the library。他现在不会在图书馆例2：Whossinginginthenextroom?It_beMary.ShehasgonetoNewYork.A.cantB.mustC.shouldntD.can注意： can 和 be able to在表示能力这一点是同义词，通常可以通用 I can speak English.=I am able to speak English.但在针对过去情况时，两者的区别意义明显，不可混用。在过去情况下，主语“潜能”的实施与否，两者有区别。比较：1）We could save his life.我们有办法救活他。 （但未必实施）2）We were able to save his life.我们得以救活他。 （付诸实施）句1）只表示主语有救人的能力，但未必实施；句2）则表示主语非但有救人的能力，而且已成功实施了。但在否定句式中，因为表示主语“无能力”，所以不存在能力的实施问题。这时，两者意义统一，可以通用。例如：I couldnt/wasnt able to pass the exam.我没能考及格。He couldnt/wasnt able to live to see his country reunited.他没能活着亲眼见到祖国的重新统一。一般说来, be able to后边的动词不定式没有被动语态。如: Im sure he is able to correct his mistakes in grammar.而不说: Im sure his mistakes are able to be corrected by him例3：In China even barren mountains_ turned into fertile fields. A)can B) can be C) is able to D) is able to beCould是 can的过去式，可以用来表示过去的能力或“可能性”I could run very fast when I was young. 我年轻时跑得很快I couldnt understand what he said at all. 我一点也听不懂他说的话例4：Mary _my letter, otherwise she would have replied before now.A) should have received B) has receivedC) couldnt have receivedD) ought to have received例5：The fire spread very quickly，but luckily everyone_ get out. A、had to B、would C、could D、was able to 表示惊异、怀疑How could you be so careless? 你怎么会这样粗心We thought the story could not be true. 我们当时以为那个故事不会是真的。可以代替can用于现在的动作，但语气较为委婉，如：Could I use your bike?我可以用一下你的自行车吗？You could do it this way.你可以把这个男孩带去（2） may的用法用来询问或表示允许（在此用法中may和第一人称连用时都以疑问句形式出现）May I ask you a question？我可以问你一个问题吗？You may take the boy there.你可以把这个男孩带去。 He may come if he likes.如果他想来，可以来They may stay in our house.他们可以在我家歇息。例6：_Iuseyoureraser,Rose?Sure.Hereyouare.A.MayB.WouldC.NeedD.Must表示说话人的猜测，认为某一事情“或许”或“可能”发生We may call on you this evening我们也许今天晚上会来看你（们）She may not like this place她可能不喜欢这个地方Might 是 may的过去形式，表示询问或允许或可能、推测等。如：Might I give you a piece of advice?我可否给你提个建议（Might 比 may更客气）He told me he might come.他说他可能来（Might与told相呼应都是过去式）I was afraid he might not like this place.我当时担心他可能不喜欢这个地主（Might 与was相呼应，都是表示过去。)【注意】：A。有时Might也可用来表示现在的事情，只是可能性比may更小一些，如：He might know her address. 他也许知道她的地址。Be careful, you might break it. 小心点，要不你可能会将它打碎BMay(might)后加动词不定式的完成式可以表示对过去的推测、认为某事在过去“可能”发生，这一用法中may和might都指过去，不过might较may更含蓄或更不肯定。如：He may (might) have watched TV the whole night.(For he looks very sleep)他可能看了一夜电视（因为他看上去非常困倦）They might ( may) not have caught the train.他们可能没赶紧上车。（3）must的用法表示“必须”或“应当”。如：We must rely on ourselves.我们必须依靠自己You must finish the work before four oclock.你必须在四点前干完这项工作例7：Anothercupoftea?No,thanks.I_beoff.Ginaiswaitingforme.A.canB.mustC.may例8：MustIgetupearlytomorrowmorning?No,_.A. youmustntB.Idontthinkyouhaveto C.youcant D.youneed例9：Itrainedheavily,sowe_stayathomewatchingTVorsurfingtheInternetallday.A.couldB.hadto C.mustmust只有现在式而无其他时态变化，通常也只用来表示现在，但有时出可以用must表示过去（多用在间接引语中），如：He told me I must do according to what he said. 他对我说，我必须按他说的做。must也可表示推测，但比may肯定得多，可译成“一定”或“准是”，如：He must be in the library.他现在准在图书馆It must be four in the morning now.现在一定是到了清晨四点钟了例10:FiftydollarsforsuchaT-shirt!You_be joking!Imserious.Itsmadeofsilk.A.mustB.needC.mayD.canmust引导的一般疑问句，否定回答是neednt或donthavetoMustIfinishmyhomeworktoday,MissLiu?No,youneednt /donthaveto。（4）have to的用法后接动词原形，表示“不得不、必须”的意思，它比must更含有“客观条件使得必须如此做”的意思。并有较多的时态，如：We have to get up early.我们不得不早起We will have to get up early tomorrow. 我们明天必须早起We had to get up early at that time.我们那时不得不早起Must和have to的区别：must表示的是说话人的主观看法，而haveto则表示的是客观需要。Must一般只有现在时，而haveto有更多的形式。在下面情况下两都就不宜换用：Its raining heavily, we cant go now. I think well have to wait till the rain stops.雨下得太大了，我们现在无法走，我想我们只能等雨停了再走We must ask for permission if we do it.如果我们要干，一定要先征得同意。例11：Can you go skating with us this afternoon?Sorry, I cant. I _ take care of my little sister at home.A.can B. may C. would D. have to（5）ought to 的用法表示“有义务或有必要”作某事You ought to finish your work before you go home.你每天回家前应把工作做完You ought not to be so careless. 你不应当这样粗心表示非常可能的事His father ought to know his address.他你亲总该知道他的地址吧If we start work right now, we ought to finish it before lunch.如果我们现在开始干，午饭前应当能干完ought to 后接动词不定时的完成时，如用肯定结构，表示过去某事该做而未做，如用否定结构，则表示过去不该做的事情发生了。You ought to have been more careful.你应当更仔细些才是（但事实是当时没有仔细行事）You ought not to have interrupted them.你当时不应当打断他们（的谈话），（但当时的事实是打断了别人的谈话。）【注意】：此用法相当于”should (not) have done”结构 例：They_discussitnow.A. oughttonot B.notoughttoC.dontoughttoD.oughtnotto例：Oughtwetocleantheclassroomnow?-Yes,we_.A.oughtB.shouldC.mustD.can（6） dare的用法dare 表示“敢”的意思，它的过去时是dared除在”I dare say”这种结构中，dare极少用作肯定结构中的情态动词一般用在否定句和疑问句中，和其他情态动词一样，dare 不随人称变化而变，后面所跟的动词不定式不带to也就是动词原形。如：I dare not tell the truth.我不敢照实说出Dare she go out alone at night?她敢一个人夜间出去吗？Dare也有实义动词形式，在现在英语中，dare用作实义动词的时候更多一些。（7）need的用法need表示“需要”，用法与dare 几乎完全相同，即用于否定句和疑问句中，本身无变化。例：Needyougotoworknow?Yes,I_.A. mustB.needC.canD.dare在肯定句中通常用need有实义动词形式，用法同其他实义动词一样，如：I think he needs to do it again.我认为他需要重新做一次。（此句中的needs是实义动词。）【注意】：need后面有名词或动名词作宾语时，need是实义动词，但后接动名词的句子相当于被动语态，如：We need some more hands. 我们需要更多的帮手The garden needs cleaning.(=The garden needs to be cleaned.) 院子要清扫了The flowers need watering.(=The flowers need to be watered.) 花要浇水了 例：8.Yourroomisfullofdust.It_.A.needclean B.needcleaningC.needtobecleanedD.needstobecleanedneed和dare作情态动词和实义动词的区别：两者作情态动词时常用于否定句和疑问句。其形式为：neednt/darent do；Need/daredo?做实义动词时可用于肯定句，否定句和疑问句。其形式为：need(needs/needed)/dare(dares/dared) to do, dont(doesnt/didnt) need/dare to do注意：句型I dare say+从句。 意思是：我肯定 = Im sure或There is no doubt that+从句。例句：I dare say /Im sure/There is no doubt that my uncle will get the money if I die.（8） shall的用法主要用于第一人称的疑问句中，表示征求对方意见。如：What shall I do now?我现在该干点什么Shall we go together?咱们一起走好吗例：What _ we do tonight.A.will B.shall C.should (9) should的用法表示“劝告、建议”，译作“应当”You should study hard.你应当努力学习You should listen to the doctors advice.你应当听大夫的话We should help each other.我们应当互相帮助例：We_helpthepeopleinneed.A. canB.oughttoC.shouldD.could表示“推测、可能”They should get home by now.他们现在该到家了The book should be available in the bookstore.这本书在书店里可能有卖的后接动词完成式时，表示过去的事情，肯定结构表示该做没做；否定结构表示不该做，但发生了。I should have written you earlier.我应当早引起给你写回信（但没写）You shouldnt have told him this.你不应当把这告诉他。（但告诉了）例：Imissedthetrain.You_methatthetimetablehadchanged.A. shouldtotell B.shouldhavetoldC.oughthavetotellD.oughthavetoldOught to和should的区别：表示出于法令规则、行为准则、道德责任等客观情况而“应该”做某事时,一般应用ought to,若用should则含有个人意见,强调主观看法.在公告、须知或条例中,出于礼貌,常用should.如：We ought to go and see Mary tomorrow,but I dont think we will.明天我们按理应该去看看玛丽,但是我认为我们不会去(此句不宜用should).You should not run alongside the swimming-pool.不准在游泳池边奔跑例：One_crossthestreetagainsttheredlight.A.oughtnot B.oughttonotC.shouldnttoD.oughtntto(10) will, would的用法主要用于第二人称的疑问句中，表示说话人向对方提出请求，would较 will更委婉些Will you help me? 你能帮帮我吗？Would you like some tea? 你想喝点茶吗？Will you please tell me the way to the station? 请问到车站怎么走？wouldyou的回答方式有以下几种：Yes,Iwill.(No,Iwont.)Sure.(Imsorry,Icant.)Allright/OK/Withpleasure.Certainly.(No,thankyou.)Yes,please.例：Wouldyoudomea favor?_.A. ThatsrightB.WithpleasureD.Notrouble(11) used to的用法后接动词原形，表示以前经常发生的动作，但现在不是这样了（通常用于肯定句中）。I used to get up early，我以前经常早起（现在不是这样了）He used to read aloud everyday. 他以前天天朗读（但现在不是了）注意：句型“be + used to”后接动名词或名词，表示“习惯“：I am not quite used to the weather, here. 我不大习惯这里的天气Are you used to the food in Beijing?你现在习惯吃北京的饭了吗？ Im used to getting up early.我习惯早起。 used to和would的区别: used to表示过去常常做现在已经不再有的习惯，而would只表示过去的习惯或喜好，不涉及现在。练习：1、Lookatthesign!Oh,Isee.We_wastewater.A. canB.mustC.mustntD.neednt2、MustIbehomebeforeeightoclock,Mum?No,you_.Butyouhavetocomebackbeforetenoclock.A. needntB.cantC.mustnt3、 _IborrowyourMP3?Sure.Hereyouare.A. May B.Should C.Must D.Would4、-He_beintheclassroom,Ithink.-No,he_beintheclassroom.Isawhimgohomeaminuteago.A. can;maynotB.must;maynotC.may;cantD.may;mustnt5、-ShallIgetonemorecakeforyou,Dad?-Thanks,butyou_,Ivehadenough.A.maynotB.mustnotC.cantD.neednt6、Eventhetopstudentsinourclasscantworkoutthisproblem,soit_beverydifficult.A.mayB.mustC.canD.need7、Heisntatschool.Ithinkhe_beill.A.canB.shallC.mustD.hasto8、_Itakethisone?A.MayB.WillC.AreD.Do9、Needthedoctor_withyoutonight?A.stayingB.stayC.staysD.tostay10. He must be in the classroom_ he?Amustnt Bcant Cisnt DCan11. Lets go to the libraryshall we? _ANo，I cant BYesI will CYes，thank you DNo，Wed better not12.- You ought to have called him yesterday-Yes, I know I_Aought to Bought to haveCought to have done Dought to have called13. -Why did you keep it a secret from me?-I _ about itAshould be told Bought to have been toldCshould have told Dought to be told14. The work _ be finished in such a short timeAwasnt able to Bcouldnt Cought Dcould15. He looks very tiredHe _ to bed too late last nightAmust go Bmust have gone Ccould go Ddidnt go16. The door _ lockAcant Bmay not Cwont Dmustnt17. As a soldier，you _ do as the head tells youAwill Bshall Cmay Dought18. How _ you be so careless?Acan Bwill Ccould Dmay19. I talked for a long time，and in the end I_ make her believe meAcould Bcan Cmust Dwas able to20. Did you scold him for carelessness ? Yes，but _ itAId rather not do BId rather not have doneCI shouldnt do DId better not do21. He neednt come