情态动词 (4)

1、情态动词的语法特征情态动词的语法特征1）情态动词情态动词不能单独做谓语，除不能单独做谓语，除ought和和have外，外，后面只能接不带后面只能接不带to的不定式。的不定式。2）情态动词没有人称，数的变化，但有些情态动情态动词没有人称，数的变化，但有些情态动词，如词，如can、will也有一般式和过去式的变化。也有一般式和过去式的变化。3）情态动词的情态动词的“时态时态”形式并不是时间区别的主要形式并不是时间区别的主要标标志，不少情况下，情态动词的现在式形式和过去志，不少情况下，情态动词的现在式形式和过去式形式都可用来表示现在时间、过去时间和将来式形式都可用来表示现在时间、过去时间和将来时间。

2、时间。will和和would： 1. would 表示过去的习惯性表示过去的习惯性 One day a week he _spend a whole day in silence.would2.will和和would表示意愿、意志，可用于各种人称表示意愿、意志，可用于各种人称If you _help me with my English, I _ be very happy. I promised that I _do my best.willwillwouldusedto 3. 在疑问句中用于第二人称，提出请求或询问。在疑问句中用于第二人称，提出请求或询问。_you tell her tha

3、t Im here? If you want help - let me know, _you? _you type this, please? _ you sit down? _you help us, please? would比比will客气委婉客气委婉WillwillWillWontWouldcan和和could：_ you offer me some kind of job?_ I help you?_ you ride a bike?_ he be at home?How _ you say that?I _ say that he has finished his work.Ca

4、n/CouldCanCanCan/Couldcouldcant1 1请求、允许请求、允许 2 2 主动提供帮助主动提供帮助 3 3能力能力 4 4 可能性可能性 5 5 责备责备 6 6 预言、预测预言、预测can和和could：can, could 表能力和表能力和be able to的区别的区别She can/is able to sing the song in English.This machine can make you feel comfortable.1can的主语是人或物的主语是人或物,beableto的主语是人的主语是人Well be able to finish the

5、 work soon.I havent been able to see the film.2can只用于现在式和过去式只用于现在式和过去式(couldbeableto可以用于各种时态。可以用于各种时态。3 be able to 表做成了某事表做成了某事may和和might ：1.1.表示说话人的猜测表示说话人的猜测/ /可能性可能性: :通常只用于通常只用于肯定句肯定句和和否定句否定句中。中。-_I use your pencil?-Yes, you_./ No, you_.2. may和和might 用于一般问句中表示委婉的请求用于一般问句中表示委婉的请求,肯肯定回答用定回答用may,否定

6、用否定用mustntMaymaymustnt3. 表示祝愿表示祝愿;但语气较正式但语气较正式: May you succeed! May you have a good journey!May+sb.+do! shall和和should：1.should表示义务、建议、劝告，意为表示义务、建议、劝告，意为 “应应该该”。 “should+ have+过去分词过去分词”表本应该在过去做表本应该在过去做但没做但没做。You should keep your promise. She should have passed the exam. _I open the window for you？（征

7、求意见）？（征求意见） _he fetch some water for you？（请求）？（请求）2.在疑问句中在疑问句中,用于第一、三人称，用来表用于第一、三人称，用来表示请求或征求意见。示请求或征求意见。ShallShall shall和和should：You shall do as I say. Tell him that he shall have the book tomorrow. Nothing shall stop me doing it. 3. shall用于第二、三人称表示允诺、警告、用于第二、三人称表示允诺、警告、命令、决心等。命令、决心等。must 的主要用法：的主要

8、用法： We must all die. You must get up early. He must be crazy. 1. 表示必然性。表示必然性。2. 表示强制或者义务。表示强制或者义务。3. 表示推测，语气非表示推测，语气非 常肯定，近乎确定的常肯定，近乎确定的 意味，一般用在肯定句。意味，一般用在肯定句。 注意注意: 1 must not 的意思是不许可，不的意思是不许可，不应该或者禁止。应该或者禁止。 We mustnt waste our time. - May I take this magazine out? - No, you mustnt. 2 must 用于一般疑问句

9、的时候，用于一般疑问句的时候，肯定回答应该用肯定回答应该用yes, please 或者或者 Im afraid so, 其否定回答应该用其否定回答应该用 neednt 或或者者 dont have to。如：。如：归纳：归纳：表可能、猜测表可能、猜测2） can一般用于一般用于疑问句疑问句、有把握的、有把握的否定否定推测推测 may/might用于没有把握的用于没有把握的肯定肯定、否定否定推测推测 must用于有确切把握的用于有确切把握的肯定句肯定句3） 对现在、未来推测：对现在、未来推测：+ do 对过去推测：对过去推测：+ have done 对此刻正在发生的事情推测对此刻正在发生的事情推

10、测: + be doing1） must / can / could / may / might (强强 弱弱)语气语气4 ) should (大概、按理应当大概、按理应当) ; will(很可能、准会很可能、准会) 也可表推测，一般只用于也可表推测，一般只用于肯定句肯定句 2. A: _ Xiao Feng find the origin of Easter from that book? B: No, he _. 1. A: _ you like to go to a special event with us on Saturday? B: Yes, I _ _.Wouldd like

11、to go with you on SaturdayCouldcouldnt find itExercise 3. A: _ I go with my friend to the harvest festival? B: Yes, you _ _. 4. A: If I want to be a doctor _ I study science? B: Yes, you _. should study scienceMay may go ( with your shouldfriends )5. A: He is very handsome. _ he play the role of the

12、 prince? B: No, he _ _. cant play the role of theCanprince 6. A: The neighbour s children are older this year. _ they stop playing tricks at Halloween? B: Perhaps, they _ _. _ _.Mightor Shouldmight stopor should stop playing tricksplaying tricks at Halloweenat Halloween1. -_ I go out to play, mum? -

13、No, you_. You should do your homework first. A. Might; wouldnt B. May; had better not C. Must; mustnt D. Need; mustntBPractice 2. -Where is Emma? -I cant say for sure where she is, but she_ be out shopping. A. can B. should C. must D. mayD3. The room is in a terrible mess; it _ cleaned. A. cant have

14、 been B. couldnt be C. may have been D. would beA4. How _ you say that you really understand the whole story if you have covered only part of the article? A. can B. must C. need D. mayA5. There _ be any difficulty about passing the road test since you have practised a lot in the driving school. A. m

15、ustnt B. shant C. shouldnt D. needntCExercise I单句改错单句改错 1. Mr. Smith looks pale. He can be ill. 2. When we worked in the same office, we will often have coffee together. 3. You must be joking. That mustnt be true. 4. Come to take the photos tomorrow morning. It may be ready by then. 5. The fire spread so fast that only one-third of the people could escape the fire.maywouldcantshouldwere able toII用正确的情态动词填空。用正确的情态动词填空。1. When we are cooking with a gas fire, we _ (can/must) keep the window open.2. Mr. Joseph has stayed in the US for several years. H