(1)表示能力，如：He can speak English better than you.
(2)在疑问句和否定句中表示“怀疑”、“猜测”或“可能性”，如：Can this green bike be Liu Dong's?
(3)表示“许可”时can可以和may换用，如：You can (may) go home now.
新浪博客
(1)表示能力，如：He can speak English better than you.
(2)在疑问句和否定句中表示“怀疑”、“猜测”或“可能性”，如：Can this green bike be Liu Dong's?
(3)表示“许可”时can可以和may换用，如：You can (may) go home now.
，这时could不再是can的过去式，如：Could
you come again tomorrow?
(5)can和be able to都可表示能力，两者在意思上没有什么区别。但是can只能有现在式和过去式，而be able to则有更多的形式，如：He will be able to do the work better.
(2)may或
(3) may在句中表祝愿。例如：
May good luck be yours！祝你顺利。
May there never be another world war. 但愿不再有世界大战。
May you succeed! 祝你成功!
3、must的基本用法
(1)must表示“必须”、“应该”之意，其否定式
(2)对以must提出的疑问句，如作否定回答时，要用needn't或用don't (doesn't) have to (不
(3)在肯定句中must可以表示推测，表示“一定”或“必定”之意，如：---- Whose new bike can it be? ---- It must be Liu Dong's. I know his father has just bought him a new one.
4、can, could, may, must后接完成式的用法
(1)can, could后接完成式的用法：①在否定句或疑问句中表示对过去发生过的事情的“怀疑”或“不肯定”的态度，Could he have said so? ②在肯定句中，可以表示过去可能做到而实际并没做到的事情，有“劝告”或“责备”的语气。如：---- When did you answer her letter? ---- Only yesterday. ---- It's too late. You could have answered it earlier, I am sure.
(2)may, might后接完成式的用法
(3)must后接完成式的用法：表示对过去某事的推测，认为某事在过去一定做到
5、have to
6、ought to的基本用法
(l)表示根据某种义务或必要“应当”做某事，语气比should强，例如：Everyone ought to obey the traffic regulations.
(3)“ought + have+
(l)dare (dared为其过去式)
(2)在现代英语中dare常用作行为动词，其变化与一般行为动词相同，如：She dares to stay at home alone at night.
8、need的基本用法
(1)need作情态动词用时，主要用于否定句和疑问句中，如：He needn't worry about us now.
(2)need也可作为行为动词用，可用于肯定句，否定句和疑问句中，其后可接名词、代词、动名词或带to
9、shall的基本用法
(1)shall用作情态动词时，用于第二、三人称，表示说话人的意愿，可表示“命令”、“警告”、“强制”、“威胁”或“允诺”等意，如：He shall go first, whether he wants to or not.
(2)在疑问句中，shall用于第一、三人称，表示说话人的征询对方意见或请求指示，如：Shall I open the door?
10、should的基本用法
(1)should作为情态动词可以表示“建议”或“劝告”，有“应该”之意，如：You should learn from each other.
(2)should后接完成式表示过去没有做到本来应该做的事情，或是做了本来不应该做的事情。如：You should have give him more help.
2. 竟会,竟然(与why, who, how 等连用, 表示意外、惊异等)
如:It is simply a miracle that rice should grow in such a place. 稻子竟能在这样的地方生长, 这实在是个奇迹.
11、will的基本用法
(1)用于各人称，可以表示“意志”或“决心”，如：I have told him again and again to stop smoking, but he will not listen.
(2)在疑问句中用于第二人称，表示说话人向对方提出请求或询问对方的意愿，如：Will you please tell me how to get to the Capital Gymnasium?
(3)will可以表示一种习惯性的动作，有“总是”或“会要”之意，如：Every morning he will have a walk along this river.
12、would的基本用法
(1)would作为will的过去式，可用于各人称，表示过去时间的“意志”或“决心”，如：He promised
(4)would可以表示过去的习惯动作，比used to正式，并没有“现已无此习惯”的含义。如：Last year our English teacher would sometimes tell us stories in English after class. / During the vacation he would visit me every week.
13、used to, had better, would rather的用法
(1)used to表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变，例如：He told us he used to play foot ball when he was young.
疑问句：Did you use to/ Used you to go to the same school as your brother?
Did you use to play chess? Yes, I did./ Used you to get up early in the morning? Yes, I did./ used to.
否定疑问句：Usen’t you to/ Didn’t you use to be interested in the theatre?
强调句：I certainly used to/ did use to smoke, but it was a long time ago.；
其反意疑问句或简略回答中，也有两种形式：She used to be very fat. didn’t she?/ use(d)n’t she?
(3)would rather意为“宁愿”，表选择，后接不带to的不定式，例如：I’d rather not say anything./ Would you rather work on a farm?/ ---- Wouldn’t you rather stay here? ---- No, I would not. I’d rather go there.
情态动词练习
1. If they _________ to do this work, he might do it some other way.
2. I was told yesterday that the company _________ me to Rome next week for a business conference.
3. Let's take a walk, ________?
A. will we
4. He was a good swimmer so he _________ swim to the river bank when the boat sank.
5. I went to the doctor's yesterday, I had to wait for half an hour before he ________ see me.
6. ---- _________ this book be yours?
7. 'We didn't see him at the lecture yesterday. '
8. They _________ the plane, or perhaps they have been prevented from coming for some reason.
9. Since the ground is white, it _________ last night.
A. had snowed B. must have snowed
10. You must be fifty, ________?
11. You must have seen him off yesterday, _________?
12. ---- That must be a mistake.
13. He had known the matter before you told him, so you _________ have told it to him.
14. How ________ so?
15. You are their teacher. You _________ care of them.
16. She is studying medical science now but she _________ a lawyer.
17. If you were in an English-speaking country, you, too, _________ English every day.
18. I did not call to make my airline reservation (预订) but I _________.
19. As a girl, she _________ get up at six every day.
20. Don't you remember that we _________ to the cinema tonight?
21. ---- Shall I tell John about it?
22. 'Would you mind if I open the window?'
23. 'Would you tell me something about the affair?'
24. M:________?
25. 'You ought to have come here ten minutes ago?'
26. 'Would you like to go out for a walk?'
27. ________ you succeed !
28. Did he need ________ then?
29. Do you think if he dares _________ in public.
30. He ________ eating American food since he came here.
31. A computer ________ think for itself; it ________ be told what to do.
32. '________ you mind my opening the window?'
33.1 didn't hear the phone. I _________ asleep.
34. You _________ me about it earlier, but you didn't.
35. The teacher told the students that they ________ keep silent in class all the time.
36. 'May I go now?' 'No, you ________. '
37. You _________ do the exercise if you don't want to.
38. You _________ pay more attention to your spelling next time.
39. The girl _________ out alone at night.
40. There ________ be a lot of small houses on both sides of the street.
A. used to
参考答案：
1~5 ABDDD
26~30 ABBCC
(5)can和be able to都可表示能力，两者在意思上没有什么区别。但是can只能有现在式和过去式，而be able to则有更多的形式，如：He will be able to do the work better.
(2)may或
(3) may在句中表祝愿。例如：
May good luck be yours！祝你顺利。
May there never be another world war. 但愿不再有世界大战。
May you succeed! 祝你成功!
3、must的基本用法
(1)must表示“必须”、“应该”之意，其否定式
(2)对以must提出的疑问句，如作否定回答时，要用needn't或用don't (doesn't) have to (不
(3)在肯定句中must可以表示推测，表示“一定”或“必定”之意，如：---- Whose new bike can it be? ---- It must be Liu Dong's. I know his father has just bought him a new one.
4、can, could, may, must后接完成式的用法
(1)can, could后接完成式的用法：①在否定句或疑问句中表示对过去发生过的事情的“怀疑”或“不肯定”的态度，Could he have said so? ②在肯定句中，可以表示过去可能做到而实际并没做到的事情，有“劝告”或“责备”的语气。如：---- When did you answer her letter? ---- Only yesterday. ---- It's too late. You could have answered it earlier, I am sure.
(2)may, might后接完成式的用法
(3)must后接完成式的用法：表示对过去某事的推测，认为某事在过去一定做到
5、have to
6、ought to的基本用法
(l)表示根据某种义务或必要“应当”做某事，语气比should强，例如：Everyone ought to obey the traffic regulations.
(3)“ought + have+
(l)dare (dared为其过去式)
(2)在现代英语中dare常用作行为动词，其变化与一般行为动词相同，如：She dares to stay at home alone at night.
8、need的基本用法
(1)need作情态动词用时，主要用于否定句和疑问句中，如：He needn't worry about us now.
(2)need也可作为行为动词用，可用于肯定句，否定句和疑问句中，其后可接名词、代词、动名词或带to
9、shall的基本用法
(1)shall用作情态动词时，用于第二、三人称，表示说话人的意愿，可表示“命令”、“警告”、“强制”、“威胁”或“允诺”等意，如：He shall go first, whether he wants to or not.
(2)在疑问句中，shall用于第一、三人称，表示说话人的征询对方意见或请求指示，如：Shall I open the door?
10、should的基本用法
(1)should作为情态动词可以表示“建议”或“劝告”，有“应该”之意，如：You should learn from each other.
(2)should后接完成式表示过去没有做到本来应该做的事情，或是做了本来不应该做的事情。如：You should have give him more help.
2. 竟会,竟然(与why, who, how 等连用, 表示意外、惊异等)
如:It is simply a miracle that rice should grow in such a place. 稻子竟能在这样的地方生长, 这实在是个奇迹.
11、will的基本用法
(1)用于各人称，可以表示“意志”或“决心”，如：I have told him again and again to stop smoking, but he will not listen.
(2)在疑问句中用于第二人称，表示说话人向对方提出请求或询问对方的意愿，如：Will you please tell me how to get to the Capital Gymnasium?
(3)will可以表示一种习惯性的动作，有“总是”或“会要”之意，如：Every morning he will have a walk along this river.
12、would的基本用法
(1)would作为will的过去式，可用于各人称，表示过去时间的“意志”或“决心”，如：He promised
(4)would可以表示过去的习惯动作，比used to正式，并没有“现已无此习惯”的含义。如：Last year our English teacher would sometimes tell us stories in English after class. / During the vacation he would visit me every week.
13、used to, had better, would rather的用法
(1)used to表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变，例如：He told us he used to play foot ball when he was young.
疑问句：Did you use to/ Used you to go to the same school as your brother?
Did you use to play chess? Yes, I did./ Used you to get up early in the morning? Yes, I did./ used to.
否定疑问句：Usen’t you to/ Didn’t you use to be interested in the theatre?
强调句：I certainly used to/ did use to smoke, but it was a long time ago.；
其反意疑问句或简略回答中，也有两种形式：She used to be very fat. didn’t she?/ use(d)n’t she?
(3)would rather意为“宁愿”，表选择，后接不带to的不定式，例如：I’d rather not say anything./ Would you rather work on a farm?/ ---- Wouldn’t you rather stay here? ---- No, I would not. I’d rather go there.
情态动词练习
1. If they _________ to do this work, he might do it some other way.
2. I was told yesterday that the company _________ me to Rome next week for a business conference.
3. Let's take a walk, ________?
A. will we
4. He was a good swimmer so he _________ swim to the river bank when the boat sank.
5. I went to the doctor's yesterday, I had to wait for half an hour before he ________ see me.
6. ---- _________ this book be yours?
7. 'We didn't see him at the lecture yesterday. '
8. They _________ the plane, or perhaps they have been prevented from coming for some reason.
9. Since the ground is white, it _________ last night.
A. had snowed B. must have snowed
10. You must be fifty, ________?
11. You must have seen him off yesterday, _________?
12. ---- That must be a mistake.
13. He had known the matter before you told him, so you _________ have told it to him.
14. How ________ so?
15. You are their teacher. You _________ care of them.
16. She is studying medical science now but she _________ a lawyer.
17. If you were in an English-speaking country, you, too, _________ English every day.
18. I did not call to make my airline reservation (预订) but I _________.
19. As a girl, she _________ get up at six every day.
20. Don't you remember that we _________ to the cinema tonight?
21. ---- Shall I tell John about it?
22. 'Would you mind if I open the window?'
23. 'Would you tell me something about the affair?'
24. M:________?
25. 'You ought to have come here ten minutes ago?'
26. 'Would you like to go out for a walk?'
27. ________ you succeed !
28. Did he need ________ then?
29. Do you think if he dares _________ in public.
30. He ________ eating American food since he came here.
31. A computer ________ think for itself; it ________ be told what to do.
32. '________ you mind my opening the window?'
33.1 didn't hear the phone. I _________ asleep.
34. You _________ me about it earlier, but you didn't.
35. The teacher told the students that they ________ keep silent in class all the time.
36. 'May I go now?' 'No, you ________. '
37. You _________ do the exercise if you don't want to.
38. You _________ pay more attention to your spelling next time.
39. The girl _________ out alone at night.
40. There ________ be a lot of small houses on both sides of the street.
A. used to
参考答案：
1~5 ABDDD
26~30 ABBCC