情態(tài)動(dòng)詞的特點(diǎn)

1、Grammar: Modal verbs,Lectured by RenQiuyu,一、情態(tài)動(dòng)詞的特點(diǎn),1 有詞義 2 沒(méi)有人稱(chēng)和數(shù)的變化。也就是說(shuō)，它在任何主語(yǔ)后形式都是一樣的，這是情態(tài)動(dòng)詞和助動(dòng)詞最大的差異。 3 有時(shí)態(tài)的變化 4 不能獨(dú)立作謂語(yǔ)，后面必須跟動(dòng)詞原形 在情態(tài)動(dòng)詞后一般要跟不帶to的不定式（ought to除外）,二、情態(tài)動(dòng)詞的種類(lèi),1) can表示體力、智力上的能力。否定式為cannot, 縮略為cant; 過(guò)去式為could couldnt eg:We can do things they cant do. Mary can type well and her mothe

2、r could type well when she was young. 2) 表示客觀可能性 eg: Man cannot live without air. 3) 表示征求意見(jiàn)或請(qǐng)求許可，表示語(yǔ)氣委婉 eg:Can I go for a swim this afternoon, Mum? Could you lend me your bicycle? No, sorry, I cant. ( couldnt is wrong) Yes, of course you can.,1. can和 could,4) can 和could 表推測(cè)（can用于否定及疑問(wèn), could肯定、否定、疑問(wèn)

3、皆可） can (could) not + V原（link.或狀態(tài)動(dòng)詞）對(duì)現(xiàn)在狀態(tài)的推測(cè) can (could) not + be + doing對(duì)現(xiàn)在動(dòng)作的推測(cè) can (could) not + have done 對(duì)過(guò)去動(dòng)作的推測(cè) eg: a. The young girl cant be our new chairman. Can/ Could the news be true? b. He cant be reading in the reading room, for I saw him in the street just no They may be arguing. But

4、I am interested in what they can/ could be arguing. c. The road isnt wet. It cant/ couldnt have rained last night. I dont know why she didnt call me yesterday. Can/ Could she have forgotten my telephone number? 5) could have done本能做卻沒(méi)有做, can have done這種結(jié)構(gòu)不存在 eg:You could have caught the first train,

5、 but you got up too late.,6) Can/ could與 be able to 的區(qū)別 A. be able to do sth.也表示能力，可以用于不同時(shí)態(tài)，前后還可以用情態(tài)動(dòng)詞must, may, might以及seem to, used to, appear to等，而can/could只用于一般現(xiàn)在時(shí)和一般過(guò)去. eg:He is able to (= can) play the piano very well. After three years of hard work, he was able to pass the entrance examinatio

6、n. The large hall will be able to hold 5000 audience. He seems to be able to work out the puzzling question. B.當(dāng)用于過(guò)去時(shí)態(tài)時(shí)，could表示能力，但有沒(méi)有做，不知；而was/were able to 指過(guò)去某種具體的能力，通過(guò)努力并做成功了，相當(dāng)于managed to或succeeded in eg:He could sing many English songs. Its known that he was able to recite many foreign poems at

7、 six.,1) may表示請(qǐng)求許可。疑問(wèn)式May I.?多為請(qǐng)求允許，通常用于正式文體 egMay I come in?No, you cant / may not.Yes, please. No, you mustnt. (強(qiáng)烈禁止，不允許)Yes, certainly Please dont.Sure. Might也可以表示允許，Might I ?和May I.?用法相近. 但might表示請(qǐng)求語(yǔ)氣遲疑委婉，回答時(shí)應(yīng)用may表示肯定 eg: -Might I ask for a photo of your family? -Yes, you may. 2)may用在句子開(kāi)頭，表示祝愿 M

8、ay + 主語(yǔ) + 動(dòng)詞原形 + 其它成分 eg:May you succeed in the coming examination! May all your dreams come true some day!,2. may 和might,3) may和 might表推測(cè)（不用于疑問(wèn)） may/might + V (系動(dòng)詞或狀態(tài)性動(dòng)詞)對(duì)現(xiàn)在狀態(tài)的推測(cè) may/might + be doing 對(duì)現(xiàn)在動(dòng)作的推測(cè) may/might + have done 對(duì)過(guò)去動(dòng)作的推測(cè) eg: a. He may know Alices address. He may not know Alices a

9、ddress. （可能不） He cant know Alices address. （不可能） Can it be true? It may be, or may not be. b. Wheres Tom? He may/might be playing football. c. -He seems know the city quite well. - He may/ might have been there before.,1)表示必要性、義務(wù)，“應(yīng)該”、“必須”的意思，否定式mustnt 表示不允許 eg You must wait for your turn. You mustn

10、t jump the queue. Must I be home before eight oclock? -Yes, you must. ( No, you neednt. / No, you dont have to.) 2） have to和must意義相近，意為“不得不”，含有“客觀需要使得必須這樣做”的意思，有時(shí)態(tài)、人稱(chēng)的變化, have got to用于口語(yǔ)，dont have to 為否定式，意為“不必要” eg She didnt have to say sorry. Do we have to answer all the questions? Next year I wil

11、l have to leave this school. 3） must 表推測(cè)（一般用于肯定句）意為：一定 否定式： cant must + V must + be doing must + have done eg: 情態(tài)動(dòng)詞must猜測(cè)性的反義疑問(wèn)句 He must be a doctor, isnt he? （表現(xiàn)在狀態(tài)， 用be） He must live near here, doesnt he? （表現(xiàn)在動(dòng)作，用do, does） He must have come here yesterday, didnt he? （表短暫性過(guò)去動(dòng)作，用did） They must have

12、been to Beijing, havent they? （表現(xiàn)在狀態(tài)，用have, has）,3 must 和 have to,4 will / would; shall,1)will表示意志意愿，用于各種人稱(chēng)，可譯為“肯”、“會(huì)”、“愿意”等，過(guò)去式為would egIf you will allow me, I will see you home. I will have nothing to do with this matter. No matter what happened, he wouldnt say a word. If he kept on making mistake

13、s, I wouldnt make friends with him. 2)will用于第二人稱(chēng)，表示有禮貌的請(qǐng)求，would為過(guò)去式，但語(yǔ)氣更委婉 eg Will you kindly hand me the watch? Bring the fruit to the dining-room, will you? - Would you do me a favor? - Yes, I will./ Sure / Of course/ Certainly. No, I wont./ Im sorry I cant. Will/ Would you please do Would you lik

14、e to do sth. would rather do sth. (than do sth.),3) would do (used to do)表示過(guò)去常常做某事,would后只能接動(dòng)作性動(dòng)詞而used to 既可以接動(dòng)作性動(dòng)詞，也可以接狀態(tài)性動(dòng)詞。 He would go to enjoy some wonderful films at night. He used to be a teacher. 4) would have done 用于虛擬，與過(guò)去事實(shí)相反 If you had helped us, we would have finished our homework ahead

15、of time. 5）shall用于第一、第三人稱(chēng)疑問(wèn)句中，表示說(shuō)話(huà)人征求對(duì)方意見(jiàn)或向?qū)Ψ秸?qǐng)示。 egShall we go and get some food? When shall he be able to leave the hospital? Shall 用于第二、第三人稱(chēng)，表示說(shuō)話(huà)人給對(duì)方的命令、警告、允諾或威脅。 eg. You shall do it./ He shall stay at home. （命令） You shall fail if you dont work hard. （警告） He shall have the book when I finish readi

16、ng.（允諾） He shall be punished. （威脅）,5 should / ought to,兩者意義基本相同，用法也相同 1）表示勸告或建議，should語(yǔ)氣比ought to 弱，意為“應(yīng)該”，否定式shouldnt, ought not to意為“不應(yīng)該” eg You should get everything ready before the examination. He shouldnt be so careless. We ought to be out in the fresh air. We ought not to take risks（冒險(xiǎn)）. 2）表示

17、應(yīng)該怎么樣卻沒(méi)有怎么樣 A. 對(duì)現(xiàn)在進(jìn)行動(dòng)作 should(ought to ) be doing / shouldnt (ought not to) be doing eg:You should be washing your clothes. Why are you playing football? You are ill. You shouldnt be working here B. 對(duì)過(guò)去動(dòng)作 Should (ought to ) have done (本應(yīng)該做卻沒(méi)有做) Shouldnt (ought not to) have done (本不應(yīng)該做卻做了) eg:You sho

18、uld have gone over your lessons. I shouldnt have eaten so much ice cream. 3) should 表推測(cè)，暗含很大的可能或有根據(jù)有把握 The film should be very good. The photo should be ready tomorrow.,6 need,可以既作情態(tài)動(dòng)詞又作實(shí)義動(dòng)詞 1) need用作實(shí)義動(dòng)詞，用在肯定句、否定句和疑問(wèn)句中，有人稱(chēng)變化和過(guò)去時(shí)形式，后接名詞、代詞、動(dòng)名詞和動(dòng)詞不定式 eg She needs more rest. You didnt need to tell him

19、 the news. The TV needs mending / to be mended. 2)need作情態(tài)動(dòng)詞時(shí)一般只用在否定句或疑問(wèn)句中，沒(méi)有人稱(chēng)和時(shí)態(tài)的變化 eg- Need we tell him about it? - No, you neednt / dont have to. You neednt finish writing the report in such a short time. He said he need not go yesterday. 3) neednt have done 本不必做卻做了 need have done幾乎不存在這種結(jié)構(gòu) Time i

20、s enough. You neednt have come in such a hurry.,7 dare,可以既作情態(tài)動(dòng)詞又作實(shí)義動(dòng)詞 1) dare用作實(shí)義動(dòng)詞，用在肯定句、否定句和疑問(wèn)句中，有人稱(chēng)變化和過(guò)去時(shí)形式，dare(s/d) to do sth, 但在否定句中，后面的不定式可帶to, 也可不帶to egHe was so brave that he dared to go alone at night at the age of five. He does not dare (to) answer his fathers question. Do you dare to tou

21、ch it? 2) dare作情態(tài)動(dòng)詞主要用于否定句、疑問(wèn)句或條件句中，沒(méi)有人稱(chēng)的變化，但是有過(guò)去式dared，但I(xiàn) dare say（常用作插入語(yǔ)）除外 eg His speech is quite excellent, I dare say, which will win him the first prize. How dare you say I am a liar? No one dared speak about it. I darent ask you, because I thought I must be wrong. If you dare do that again, t

22、he teacher will scold you.,情態(tài)動(dòng)詞的猜測(cè)性用法總結(jié),我們用must（一定）, can（可能）, could（可能）, may（也許）, might（或許）表示“猜測(cè)可能性”。Could , might比can, could在口氣上要委婉些?？赡苄杂纱蟮叫∨帕袨椋簃ust can(could) may might,1）對(duì)現(xiàn)在或?qū)?lái)的猜測(cè) Modal. Verb + (not) do sth She must / may / might know Lilys address. He must / may / might leave for Beijing tomorro

23、w. He cant / couldnt / may not / might not be able to pay the house. - Its not mine. Whose can / could it be? （疑問(wèn)句中一般不用may, might） - It could be Johns. / It cant / couldnt be Jims. 2）對(duì)現(xiàn)在進(jìn)行的動(dòng)作的猜測(cè) Modal. Verb + (not) be doing sth They must / may / might be waiting at the school gate. He cant be readin

24、g in the classroom for I saw him in the street just now. She cant / may not / might not be eating anything now. 3）對(duì)過(guò)去動(dòng)作或已經(jīng)完成的猜測(cè) Modal. Verb + (not) have done sth He must / may / might have made much progress recently. He cant / couldnt / may not / might not have finished his homework. Can / Could he

25、 have got what he wanted?,注：1 must作為猜測(cè)只能用于肯定句，mustnt表示不能，不許，不是猜測(cè) 2 can作為猜測(cè)只能用于否定句，疑問(wèn)句，但could可用于肯定句、否定句和疑問(wèn)句 3 can have done, mustnt have done作為猜測(cè)不存在，could have done表示本能做卻沒(méi)有做 4 may, might作為猜測(cè)一般不用于疑問(wèn)句,1、English is a language that many people around the world not speak perfectly but at least_ understand

26、. A. may; can B. would; might C. will; must D. could; might,【答案解析】根據(jù)句意和句子的語(yǔ)氣可知，第一空表示一種可能性，用may not speak 可能不會(huì)說(shuō)；第二空表示有某種能力。答案A。,2、Didnt they come to the party last week? Yes. They didnt want to come with us at first, but then we _ persuade them. A. Would B. could C. were able to D. had to,【答案解析】根據(jù)上下文語(yǔ)境及講話(huà)人語(yǔ)氣，選項(xiàng)動(dòng)作表示經(jīng)過(guò)努力才完成的。在這種語(yǔ)氣的肯定句和疑問(wèn)句中，常用be able to，在否定句中可用can。答案 C。,3、 I promise her daughter _ get a nice present on her birthday. Will it be a big