情态动词讲与练情态动词一情态动词 can_ cant_ May_ may not_ Must_ mustnt_ 二、情态动词的特点1. 情态动词无人称和数的变化, 2. 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。 3. 个别情态动词有过去式, 过去式用来表达更客气, 委婉的语气, 时态性不强, 可用于过去，现在。三、情态动词的用法1. can/could； cant/couldnt (否定)1) 表示能力, 意为“能、会”, 例如：I can speak a little English. - Can you ride a bike? I cant swim. - Yes, I can. / No, I cant.2) 表示请求或允许，多用于口语中，意为“可以、能”等 You can go home now. 现在你可以回家了 - Can I borrow your bike? You cant stop your car here. - Yes, you can. / No, you cant.3) 用于否定句、疑问句中，表示猜测、怀疑或不肯定. Lucy cant be at home now, she went to the park just now. Where can it be? I cant find my football.【注意：】1）. could 是can的过去式, 有两种用法, 一种表示过去式；一种用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在。2）. be able to 意为“有能力，能够做.”, 相当于can/could, 但它有人称，数和时态的变化。2. may; may not (否定)1) 表示“请求，许可”，此时与 can 同义，可以互换使用 May I borrow your bike? Can I borrow your bike? Yes, you may. / No, you may not. Yes, you can. / No, you cant.2) may/might表示不太肯定的猜测，意为“有可能”Lucy may come to school late today.It might rain today.【注意】：might 是may 的过去式, 有两种用法, 一种表示过去式，一种表示更加委婉, 客气的语气或对可能性的怀疑。3. must; mustnt (否定)1) must(“必须”, 表示命令)，mustnt(“一定不能”, 表示强烈禁止.) You must go to bed before 22:00pm.You mustnt play with fire. Its dangerous!-Must I write down the sentences？ -No，you neednt. (-No,you dont have to) 注意：在回答must的疑问句中，否定回答用neednt或dont have to表示“不必”，不用mustnt2) must 还可以表示非常肯定的猜测，意为“一定”The girl in a red skirt must be Lucy. 3) must/ have to 的区别：. must表示必须，强调主观上的愿望；have to表示“不得不”，强调客观需要 You must go be bed before 22:00pm. My bike is broken, so I have to go to school on foot. have to 有人称、数、时态的变化；must则没有。I have to clean the classroom today.She has to finish her homework first.It was late, he had to go to school without breakfast.【习题】1. -Must I finish the work today? -No,you . You can finish it tomorrow. A. mustnt B. cant C. shouldnt D. neednt 2. - I swim here? -Im sorry. Children swim alone here. A. Must cant B. May must C. Can mustnt D. Cant can 3. -Meng Fei broke his arm while recording If You Are The One in Beijing. -Really? Then perhaps he host TV programmes for some time. A. neednt B. mustnt C. shouldnt D.cant 4. -What do you want to eat for lunch? I will prepare earlier today. -Honey, you . Lets go out to have something different. A. mustnt B. cant C. shouldnt D.dont have to 5. Thomas, please be quiet. The others hear very well. A. cant B. mustnt C. shouldnt D.neednt 6. -You see, a man is cutting a tree on the Moon. -It be true. The teacher says there is no air on the moon. A. cant B.may not C. shouldnt D.mustnt 7. -Can I go fishing with you,Dad? -No, you . You stay at home and do your homework first. A. wont may B. cant must C. shouldnt ought D. neednt should 8. Anna hasnt come to school today. I think she be ill. A. can B.has to C. may D.should 9. -Fifty dollars for such a T-shirt! You be joking! -Im serous. Its made of silk. A. must B.need C. may D.can10. _ _I go and apologize to my teacher for my mistake? A. Should B.Need C.Can D. May 11. May I stop my car here,sir? -No,you_. A.may not B.mustnt C.cant D.neednt 12. _I change the bulb(灯泡) now? -No,you may not. You_switch off the electricity. A.Can;need B.May;must C.Must;must D.Can;must 13. John_ come to see us tonight, but he isnt very sure yet. A.may B.can C.has to D.must 14. My mother is ill.So I _to look after my little brother. A.must B.may C.have to D.should 15. Im afraid it _rain tonight. A.can B.could C.may be D.might情态动词（should ought to） 一、had better的用法 1. had better 是固定词组，意思是“应该；最好”，后接不带 to 的不定式，其用 法相当于情态动词，动词 had 没有人称或数的变化。 1) Youd better go there by bus. 你最好是坐公共汽车去那里。 2) Wed better not tell him the news. 我门最好不要告诉他这个消息。二、should的用法 1.情态动词should 常用来表示劝告、建议或义务，意思是“应该”，： 1）You shouldnt come to such a decision hastily . 你不应该匆忙作出这样的决定。 2）The party should be great fun . 那个集会一定很有意思。 1. Youd better _ late next time . A. dont B. not be C. not being D. wont be 2. - Can I leave this door open at night ? - You _ better not . A. should B. would C. could D. had 3. - Lets go to the cinema , shall we ? - _ . A. Yes , I shall B. No , I cant C. Yes , thank you