GRAMMAR
情态动词（一）
【观察】 请仔细观察下列句子中情态动词的用法，并归纳总结。
1. ①Even top students can make mistakes in exams.
②Anna may know Tom’s address.
③If you’re not careful, you could get into trouble.
④Do you think Mr. Smith might be here on time?
⑤ — It must be our headmaster.
— No, it can’t be him. He has gone to Beijing. It may be Mr. Zhang.
⑥The rescue team should arrive by 5 o’clock this afternoon.
2. ① She can speak five languages.
② I couldn’t get tickets; they were sold out.
3. ① You can have my seat. I’m going now.
② Could I have a drink of water, please?
③ — May I smoke here?
— Yes, of course.
④ Will / Would you please lend me your car tonight?
⑤ Shall we go out and have a walk after dinner?
⑥ Shall Tom go there with me tomorrow?
4. ① Ask, if you will, who the owner is.
② I would ask such questions when I was at school.
5. ① You shall be punished if you break the rule.
② Tell her that she shall have the bike tomorrow.
6. ① We should take good care of our children.
② You should give up smoking and drinking.
7．① All passengers must wear seat belts.
② You mustn’t move any of the books in my bag.
【自我归纳】
1. can / could, may / might, must / can’t, should都可表示可能性。
①can, may表示可能性的区别：can常用来表示理论上的、按常理推断的抽象的可能性；may常用来表示实际的、马上能应验的具体的可能性。（如第1组第①②句）
②could, might表示推测时，并非表示过去，而表示可能性较弱。（如第1组第③④句）
③must表示推测时，语气比较肯定，意为“肯定，一定”，其否定式多用_____。（如第1组第⑤句）
④should 用来表示一种估计的情况，可译为“按理应当……，估计……”。（如第1组第⑥句）
2. can表示能力，could表示过去具有某种能力。（如第2组句子）
3. can表示许可或请求，可与may互换使用；will / would表示征求意见或提出请求，此时would并不表示过去，而表示委婉语气；shall可以用于主语是第_____、三人称的疑问句，表示征求意见或许可。（如第3组第⑤⑥句）
4. will表示现在的习惯或意愿，would用于描述过去的习惯或例行的活动，意为“过去常常”。（如第4组句子）
5. shall可用于主语是第二、三人称的陈述句中，表示允诺、警告、命令或威胁等。（如第5组句子）
6. _____表示义务、责任或建议、劝告。（如第6组句子）
7. must表示“必须做某事”，其否定式_____表示“禁止”。（如第7组句子）
【知识拓展】
1. can表示“能够”时与短语be able to同义，但can只用于一般现在时或过去时，而后者可用于各种时态。另外，can表示某人有某种能力，而be able to表示某人 通过努力、克服困难做成某事，相当于succeed in doing sth.；叙述过去事实时，最好用was / were able to，因为could只表过去具有某种能力。如：
Can you understand the different kinds of English these people are using?
Two years later, he was able to speak very good Chinese.
2. 以could或would提问时，就不能再以could或would作答，而应该用can或will来回答。如：
— Could I borrow your dictionary?
— Yes, of course you can.
3. should用于why / how should ...或It’s + adj. + that ...句型中表示惊讶，译为“竟会”。如：
I don’t know why she should have left her wallet behind.
It’s astonishing that he should be so rude to you.
4. 回答含must（必须）的问句时，肯定回答用must，否定回答要用needn’t / don’t have to。如：
—Must I finish my homework at school?
—Yes, you must. / No, you needn’t / don’t have to.
5. could, might, would, should都可表示委婉语气。如:
I wonder if you could let me use your cell phone.
Might I know your telephone number?
【同步练习】
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
1. —Shall I inform him of the change of the schedule right now?
—I am afraid you _____, in case he comes late for the meeting.
A. will B. must C. may D. can
2. — No one _____ be compared with Yao Ming in playing basketball.
— Oh, you are really his big fan.
A. can B. need C. must D. might
3. It _____ be the postman at the door. It’s only six o’clock.
A. mustn’t B. can’t C. won’t D. needn’t
4. — Will you read me a story, Mummy?
— OK. You _____ have one if you go to bed as soon as possible.
A. might B. must C. could D. shall
5. If you _____ smoke, please go outside.
A. can B. should C. must D. may
6. The police still haven’t found the lost child, but they’re doing all they _____.
A. can B. may C. must D. should
7. —Why didn’t you come to Simon’s party last night?
—I wanted to, but my mom simply _____ not let me out so late at night.
A. could B. might C. would D. should
8. Just be patient. You _____ expect the world to change so soon.
A. can’t B. needn’t C. may not D. will not
9. — I haven’t got the reference book yet, but I’ll have a test on the subject next month.
— Don’t worry. You _____ have it by Friday.
A. could B. shall C. must D. may
10. Doctors say that exercise is important for health, but it _____ be regular exercise.
A. can B. will C. must D. may
11.“You _____ have a wrong number,” she said. “There’s no one of that name here.”
A. need B. can C. must D. would
12. —_____ I take the book out?
—I’m afraid not.
A. Will B. May C. Must D. Need
13. The traffic is heavy these days. I _____ arrive a bit late, so could you save me a place?
A. can B. must C. need D. might
14. One of the few things you _____ say about English people with certainty is that they talk a lot about the weather.
A. need B. must C. should D. can
15. What do you mean, there are only ten tickets? There _____ be twelve.
A. should B. would C. will D. shall
Keys:
【自我归纳】 can’t; 一; should; mustn’t
【同步练习】
1-5 BABDC 6-10 ACABC 11-15 CBDDA
