1、情態(tài)動詞,情態(tài)動詞 情態(tài)動詞具有一定得詞義，沒有人稱和數(shù)的變化，不能單獨(dú)構(gòu)成謂語，和謂語動詞連用表示委婉語氣或表示愿望、態(tài)度或推測等意義。,一、情態(tài)動詞的類型和特征 情態(tài)動詞的類型 只作情態(tài)動詞的有：must; can(could);may(might) 只作情態(tài)動詞也可作實(shí)義動詞的有：need , dare 可作情態(tài)動詞也可作助動詞的有：will(would); shall(should) 具有情態(tài)動詞的某些特征的有：have to; ought to; had better,2. 情態(tài)動詞的特征 (1). 有一定的詞義，但不能單獨(dú)作謂語，必須和行為動詞或系動詞連用，構(gòu)成謂語。 (2)表示說

2、話人的態(tài)度或語氣，無人稱和數(shù)的變化（have to例外，其第三人稱單數(shù)形式為has to） He has to walk home. 情態(tài)動詞后面跟的動詞須用原形。,二、情態(tài)動詞的用法 1. Can的 用法 常用來表示能力，意為“能，會”。 eg：She can swim fast, but I cant. 表示請求或許可，意為“可以”。 eg: Can you go shopping with us? 表示推測，意為“可能”，常用于否定句或者疑問句中，此時cant 意為不可能。 eg: Can the news be true？ That cant be our teacher. He is

3、 on a visit to the Great Wall.,-I think Miss Gao must be in the library. She said she would go there. -No.She _be there. I have just been there. A. cant B. mustnt C. neednt D. wouldnt,4） cant 可用來作May I .？的否定回答 -May I go surfing alone this afternoon? -No, you cant . Its dangerous. 5) can和 be able to

4、兩者都是表示“能力”是用法相同，但can只有原形和過去式could兩種形式，其他時態(tài)要用be able to來表示。另外，be able to常常有“成功做了某事”的意味 Jim cant speak English. We were able to reach the top of the maintain at noon.,2. Could 的用法 can的過去式，意為“能，會”，表示過去的能力。 eg: He could write poems when he was 10. could 在疑問句中，表示委婉的語氣，此時could沒有過去式的意思。 eg: Could you pleas

5、e speak a little louder? Could I use your pen? Yes, you can/ No, you cant .,-Could I cross the street here? -Of course you _. could B. can C. are able to D. will,3. may 的用法 may 表示請求、許可，意為“可以”，比can要正式。 eg：May I ask you a question? You may go home now. 表示推測，談?wù)摽赡苄?，意為“可能、也許”，一般用于肯定句。 eg：It may rain tomo

6、rrow. She may be at home. may 的過去式為might，表示推測，可能性低于may。 eg：He is away from home. He might be sick. (4) may表示祝福 May you be happy!,(5)can和may 1) Can和may均可用來征求意見或許可，意為“可以”，一般可互換使用 Can/May I help you? 2)may 和can 表示可能性時的區(qū)別： 在肯定句中用may, might, 不用can； 在疑問句中表示推測用can； 在否定句句中用cant（不可能） She may be in the classr

7、oom. Where can they be now? That cant be true.,(6) may be 和 maybe 用法區(qū)別 常用位置 may be may 為情態(tài)動詞，be動詞原形 句中，做謂語 maybe 副詞，大概、也許， 相當(dāng)于perhaps 句首，作狀語 He may be wrong, but Im not sure.,-Have you decided which senior high school to choose? -Not yet. I _go to Moonlight School. A.must B.may C.need D. should -Wha

8、t will the weather be like tomorrow? -It _be rainy, cloudy or sunny. Who knows? must B. might C.shall D. should,情態(tài)動詞練習(xí) 1講解 1.-_I have a look at your new watch? -Yes, please. May B. Need C. Dare D. Must 2.Tom is young but he _fly a kite by himself. may B. can C. need D.must,3.The work is too hard for

9、 him. He _finish it on time. cant B. mustnt C. shouldnt D. neednt 4. The bookstore was open, so I _buy the book. can B. cant C. did can D. was able to,5. Last year I _drive. I used take the bus. could B. couldnt C. should D. shouldnt 6. -Could we smoke here? -Im afraid you _. couldnt B. cant C. are

10、able to D. will,7.-I hear youve got a new iPhone 4S._ I have a look? -Yes, certainly. May B. Do C. Shall D. Should 8.-Wheres Lucy? -Im not sure. She _in the school library. maybe B. must be C. may be D. will be,9.-Where is Tom? -_he is at home. He didnt feel well yesterday. May be B. Maybe C. May 10

11、.-_ I swim here? - Im sorry. Children _swim alone here Must; cant B. May; must Can; mustnt D. Cant; can,4. Must 的用法 must表示“一定要，必須”。否定形式是mustnt，表示 “禁止，不許可”。 eg：You must stay here until I came back. You mustnt park your car in front of the entrance. 對must引導(dǎo)的疑問句，肯定回答為must，否定回答為 neednt或者dont have to。 eg

12、：-Must I finish my homework now? -No, you neednt., must 常常指有根據(jù)的，比較有把握的推測，意為 “一定是，準(zhǔn)是”，這種用法只能用于肯定句當(dāng)中。 eg：The light is on. He must be at home now. 當(dāng)must表示肯定判斷、推測的時候，其反意疑問句要用實(shí)際問句的助動詞來構(gòu)成。 eg：She must have finish writing, hasnt she?, must 和have to must側(cè)重于個人意志和主觀上的必要，意為“必須，應(yīng) 該”。 eg：I know I must study hard

13、. have to 側(cè)重于客觀上的必要，意為“不得不”。它有一 般現(xiàn)在時第三人稱單數(shù)形式has to 和過去形式had to。 eg：My brother was very ill, so I had to call the doctor at midnight. have to的否定形式是dont have to, 相當(dāng)于neednt, 意為“不必”；mustnt 表示“禁止，不允許”.,(5) cant 和 mustnt 表否定推測時應(yīng)用cant, mustnt 意為“禁止，不允許”，不用來表推測，在肯定句中用must表推測，意為“一定”,- Mom, must I clean my ro

14、om now? - No, you _.You can do it tomorrow. cant B. neednt C. mustnt D. shouldnt,5.need 的用法 need表示“需要，必須”，主要用于否定句和疑問句當(dāng)中，否定形式為neednt,意為“沒有必要，不必”。用need提問時，肯定回答是must，否定回答為neednt. eg：-Need I stay here any longer? need可作實(shí)義動詞，此時還有人稱，數(shù)和時態(tài)的變化，后面多接動詞不定時。 eg：I need to do it right now. He needs to learn more a

15、bout the girl.,注意： 對need 的詞性判斷常為難點(diǎn)，need后加to do說明need為實(shí)義動詞，用助動詞提問或否定；need后加doing表示被動意義；若need 后加do的動詞原形，則need為情態(tài)動詞 You neednt see him, but I must. You dont need to come if you feel sick.,(6). dare 表示 “敢于”， 用作情態(tài)動詞時，無人稱變化，只用于否定句、疑問句和條件句 Mary dare not touch the snake. 用于實(shí)義動詞時，要注意人稱和時態(tài)的變化，后面跟不定式 I have ne

16、ver dared to tell him about it. 注意：dare作實(shí)義動詞時，其疑問句或否定句后面的不定式符號常省略。 He didnt dare (to) disobey.,You _ swim in this part of the lake. Its dangerous. mustnt B. neednt C. wont D. may not I enjoy the party very much, but I _ go home. Its too late. A . have to B. may C. mustnt D. shouldt,6. shall, should,

17、 will, would的用法 shall常用于疑問句當(dāng)中，表示征求對方的意見（多用于第一、三人稱），用在第一人稱或第三人稱的疑問句中 eg：shall we go out for a walk? Shall he come at once? 一般回答： Yes, please./ All right./ No, thank you. Shall用于第二、第三人稱，表示說話人給對方命令、警告、允諾或威脅。 eg: You shall fail if you dont work harder. （警告） He shall have the book when I finish reading.

18、（允諾） He shall be punished. （威脅）,should意為“應(yīng)該”?？杀硎緞窀?、建議、義務(wù)、責(zé)任等。 eg：We should protect the environment., will表示主語的決心或意愿；也可表請求或詢問，用于第二人稱。 eg：I will never do that again. I will help you if Im free this afternoon. Will you pass me the book? will表示習(xí)慣、請求，固有性質(zhì)等。 eg: Everyday he will sit here hour after hour d

19、oing nothing.（習(xí)慣） Will you help me with my English?（請求）,7. had better的用法 had better 意味“最好”，沒有人稱的變化，后接不帶to的不定式，其否定形式為had better not. eg: We had better go now. You had better not give the book to him.,- How was the youth club last night, Mark? -It was great fun. You _have come. Must B. can C. should D

20、. may You look tired now. You _stay at home and have a rest. had to B. had better C. would like to D. would rather,PS: 在英語中，我們可以用其他多種方式提出我們的建議或征求對方意見。 (1).用“Lets do.”來提出建議。 e.g. Lets go for a walk after supper. (2).用“What/How about.?”來提出建議；about后接名詞或動詞ing形式。 e.g. What about/How about a drink? What a

21、bout/How about taking Tom with us?,(3).用“Why not.?”來提出建議，表示“何不”not面后接動詞原形。“Why not.?”實(shí)際上是“Why dont you/we.?”的簡略形式。 e.g. Why not meet at the school gate at eight? Why dont we stay here another day? (4).用“Would you like.?”來提出建議，意思是“你想要嗎?”Would you like后可接名詞或不定式。如： Would you like a cup of tea? Yes, ple

22、ase. No, thank you. Would you like to go and see her? Yes, Id like to. No, thank you,“去游泳好嗎?” Shall we go for a swim? Lets go for a swim，shall we? What about/How about going swimming? Why not go for a swim? Would you like to go for a swim?,will will在there be句型中的形式及其句式變換。將有 由于“一般將來時”的結(jié)構(gòu)可以用“will+動詞原形”來表示， 所以there be句型的一般將來時的形式就是there will be。（一定不能說there will have） There are many students in our school. There will be many students in our school.,含有情態(tài)動詞的疑問句的回答 對may引出的問句，