Grammar and usage(1): Modal verbs: general introduction名师教学设计1

情态动词教案

夏海存

知识概括

1. can, could (1)表示能力；能，会

I can see a bird in the sky. Two eyes can se more than one. (2)可能，会(表示客观的可能性) Anybody can make mistakes. If you don’t try hard, you can fail. (3)表示允许，许可，请求；可以，能，和may相近，但不如may正式

Can I go with you? ---Could I borrow your bike? ---Yes, I can. (4)表示推测(主要用于否定句，疑问句和感叹句) 对现在发生事情的推测：can

be/ do(也可用could,可能性较小) 对过去发生事情的推测：can/ could have been/ done ①---Some one is knocking at the door. ---Can it be our headmaster? ---No, it can’t be him. He’s gone to shanghai. ②How can you be so careless! ③It can’t have rained last night. ④Can the news be true? (5)can, could用语疑问句中表示愿意，征求意见

Can you do me a favor? Could you wait a few minutes? 注意：could比can在语气上要委婉

(6)can, could, be able to 区别：

①can只有两种时态，be able to 有多种时态

②指能力时can/ culd与be able to可以互换，但表示确实使用了这个能力并成功地做成了某事时，要用be able to. 如：He could swim, but he didn’t jump into the river to save the boy. I was able to speak English when I was young, so I began to translate a book from then. 2. may, might (1)表示允许，可以

You may sit here. May I ask you a question? ---May I smoke here? ---Yes, please.(or Certainly) ---No, yu mustn’t (or can’t). (2)表示推测；可能，或许(通常用于肯定句)

对现在发生事情的推测：may/ might be/ do 对过去发生事情的推测：

May/ might have been/ done She may be here today. It may be Mary, forshe has returned.

I might have seen him before. May, might都可以表示推测，但might不仅在时态上表示过去，而且可能性比may要小。

(3)表祝愿

May you succeed/ May God bles you. 3. must(主观) (1)必须，应该，一定

We must study hard. ---Must I finish my homework today? ---Yes, you must. ---No, you needn’t.(or don’t have to) (2)must表示推测，表示很有把握的判断或推断，只用于肯定句。

对现在发生事情的推测：must be/ do(否定句can’t be/do) 对过去发生事情的推测：must have been/ done(否定句can’t/ couldn’t have done) He must be seventy now. There must be something wrong with you bike. You must have met the girl. (3)表示“偏偏，非得”

4.have to(客观) 有时态和人称的变化，否定式：don’t have to

比较：

We mustwork hard now. I have to go there for someone is waiting for me. 注意：mustn’t不允许，禁止，绝不可以

Don’t have to(haven’t got to)=needn’t不必

5. shall (1)用于一、三人称的疑问句中，表示征求意见或提出请求。

Shall I start my work now? Shall he go with me? (2)用于二、三人称的陈述句中，表示给对方的命令、威胁、警告、允诺等。

You shall go at once. He shall be punished. 6. should和ougth to (1)应当、应该ougth to比should语气稍强

You should(ought to)help each other. She should not(ought not to)answer my questions. (2)Should可能表示说话人的某种感情，如：惊奇、意外、愤怒、遗憾、失望等，尤其与why连用时

Why should you do that? Why should you be so careless? (3)表示推测和可能性

There should(ought to)be no problem. 1

They should get there now. They should be ready at 2:00 (4)表示虚拟：应该做(而未做),含有责备或后悔的语气结构；

should/ ought to have done You should(ought to)have arrived here earlier. I shouldn’t have wasted so much time. (5)should like=would like常用于第一人称，口语中，表示愿意，比较委婉。

I should like to go with you. 7. will (1)用于各种人称，表示意愿、决心、打算

No one will say he is wrong. I’ll help you if you need. 注意：在条件状语从句中，可用will表示意愿。

If you wil lget the book, I’ll give after it.如果你愿意看这本书，等我看完就给你。

(2)用于第二人称的疑问问中，表示有礼貌的请求。

Will you give me some advice? Will you please open the door? (3)表一种习惯或自然规律，可译为“总是”。

Oil will float on water. He will talk four hours if you give him the chance. 8. Would (1)表示过去时间的意志，意愿，决心，打算

No one would tell you the truth. (2)在疑问中用于第二人称，表示有礼貌的请求。比will婉转，客气。

Would you let me in? Would you tell me the way to the station. (3)与would搭配使用的短语

would rather do…than do…

would like sth/ to do sth Would you mind doing Would you please do (4)表示过的习惯动作

He would go swimming in summer when he was young. 9. used to 客观地说明过去的情况，过去常常或曾经做某事只有过去时

否定：didn’t use to 或usedn’t to There used to be a bus stop at the corner. 注意：used to和would区别：

Used to说明过去和现在的对比，强调过去曾如何如何，但现在这种情况已经不存在了。如：I used to smoke, but it’s six years since I smoked. Would表个人兴趣，只强调过去曾经有某种情况存在，现在的状况不与之对比。

I would sit in the yard at night listening to music. 10. need (1)必要，必须，需要，仅用于否定句和疑问句中。

---Need I tell her the answer? ---Yes, you must.

---No, you needn’t You needn’t worry about her. We needn’t go so early, need we? (2)表示虚拟，不必做某事(实际上却做了)结构为needn’t have done You needn’t have waited for me. You needn’t have gone there. (3)need可做实义动词，“需要”，可用于各种句式，有时态，人称和数的变化。

need sth/ need to do sth/ need doing= need to be done He doesn’t need any help. I need to go tomorrow. Your homework needs to be finished as soon a possible. My room needs cleaning. 11. dare (1)敢，(过去式:dared)无人称和数的变化。常用在疑问句，否定名或条件句

He dare not go out at night. I dare say you made another mistake. (2)可用做实义动词，有人称，时态和数的变化，后跟不定式

He doesn’t dare to say anything. 12. 关于含有某些情态动词的反意疑问句

(1)must当must表示命令时，反意疑问句用needn’t如：

He must hand in his homework now, needn’t he ? 当must表示推测时，反意疑问句与实际情况保持一致，即与把must删掉后的陈述句的反意疑问句保持一致，例：

①He must be a teacher, isn’t he?他肯定是个老师，不是吗？

比较：He is a teacher, isn’t he? 他是个老师，不是吗？

②He must have finished his homework, hasn’t he? 他肯定已经完成作业了，不是吗？

比较：He has finished his homework, hasn’t he? 他完成作业了，不是吗？

③It must have rained last night, didn’t it? 昨天晚上肯定下雨了，不是吗？

比较：It rained last night, didn’t it? 昨天晚上下雨了，不是吗？

(2)含有can’t的陈述句的反意疑问形式当can’t表示没能力做某事时，反意疑问句用can sb。如：jack can’t speak English,can he?杰克不会讲英语，会吗？

当can’t用于表推测时，反意疑问句由实际情况决定，即由去掉can’t后的真实陈述句决定。

例：

①Jack can’t be a teacher, is he? 杰克不可能是一位老师，是吗？

比较：Jack is not a teacher, is he? 杰克不是一位老师，是吗？

②He can’t have finished his homework, has he? 他没做完作业，不是吗？

③By the time we went there, he couldn’t have finished his job, had he? 比较：By the time we went there, he hadn’t finished his job, had he? 2

昨天我们到那儿时，他还没做完工作，是吗？

3