must 的用法
Ⅰ must“必须，一定要”表示说话人的主观看法。
1 可用于肯定句、否定句或疑问句，用于否定句时，mustn’t的意思是“一定不要”“不能”"不准"，而不表示“不必”。如：
（1）You must finish it today. 你一定要在今天完成它。
（2）You must see the doctor. 你一定要看医生。
（3） We mustn't think only of ourselves. 我们可不能只考虑自己
2 在回答must引起的问句时，肯定回答，用must,否定回答用，needn't 或者don't have to.
Must I go so soon?
yes ,you must.(No,you needn't.No,you don't have to.)
3 其后可接被动结构或进行形式：
(1) Something must be done to stop it. 必须采取措施来阻止它。
(2) I think I must be going. I think I must be going. 我想我得走了
Ⅱ 表示推测。意为“准是”、“一定是”
1 通常只用于肯定句，在否定句或疑问句用 can 代之：
(1) It must be true. 那一定是真的。 . 比较：Can it be true? 那可能是真的吗? / It can't be true. 那不可能是真的。
(2) 后接动词原形，表示对现在情况的推测：
He must be wrong. 他一定错了。
The man must have a lot of money. 这个人一定有不少钱。
注：must 表示对现在情况的推测后接动词原形时，该动词通常为状态动词(如 be, have, know 等)，若为动作动词，通常要转换其它说法。“他一定会赢”，通常不说He must win，可说He is sure to win。(He must win的意思是“他必须要赢”)
(3) 其后可接进行式或完成进行式，用以谈论一个正在进行的动作：
He must be writing a letter to his girl friend. 他一定在给他女朋友写信。
Someone must have been smoking here．一定有人一直在这里抽烟。
(4) must have done，用来谈论已发生的情况：
He must have arrived already．他一定已经到了。
I didn't hear the phone. I must have been asleep. 我没有听到电话铃，我一定是睡着了。
4. 表示“非要，偏要”有时表示不巧，有时表示固执，通常都是指令人不快的事：
Must you make so much noise? 你就非得弄出这么大的声音吗？
Why must you always interrupt me? 你为什么硬是老要打断我？
We were ready to leave, but the baby must catch cold. 我们刚准备好要走, 可孩子偏偏得了感冒。
Just when I was busy, the neighbor must come and chatter. 正当我忙碌的时候，邻居偏偏过来聊天。正当我忙碌的时候，邻居偏偏过来聊天。
5 must 和 have to 的区别
must 表示说话人的主观看法，“必须，一定要”，have to表示客观需要“不得不”
All visiters must report to reception 所有来宾必须到接待处报道。
He had to pay off the debt.他不得不还清债务。
配套练习：
1 .(2011全国卷II,8)
If you ______ smoke, please go outside.
A. can B. should C. must D. may
答案 C
解析：考查情态动词的用法。句意为“如果你非得要抽烟，请到外面去抽。”must (表示主张)一定要，坚持要。根据后一句please go outside的要求，选C。
2 .（2011福建卷,25）
——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
答案 B
解析：考查情态动词的用法。句意为“——需要我现在就通知他计划有变吗？——恐怕你得这样做，以防他开会迟到。”must (表示必要、命令或强制)必须,得。根据后半句，选B。
3 .(2011辽宁卷,21)
If you ______ go, at least wait until the storm is over.
A. can B. may C. must D. will
答案 C
解析：考查情态动词的用法。句意为“如果你非得走话，至少也要等到这暴风雨过去后。”can可以，能够；may 可能，许可；must(表示主张)一定要，坚持要；will将要，愿意。根据后句的劝告，选C。
4 （2010安徽32）
Jack described his father, who ______ a brave boy many years ago, as a strong–willed man
A. would be B. would have been C. must be D. must have been
答案：D.
考点：本题考查情态动词推测用法。
解析：句意为“杰克把他的父亲描述为一个意志坚强的人，他的父亲多年前肯定很勇敢。”
用must have been表示对过去事情的肯定推测。
5 （2010江西23）
I have told you the truth. ______ I keep repeating it?
A Must B Can C May D Will
答案：A
考点：考察情态动词的用法。
解析： must 必须, 一定 can 可以, 能够 may 也许 will 意愿, 倾向性动作, 前半句说我
告诉你事实了, 这里用的是现在完成时, 表示过去的动作对现在造成了影响, 既然我已经
说了, 我还必须重复一遍吗？
6 （2010辽宁26）
Doctors say that exercise is important for health, but it _______ be regular exercise.
A．can B．will C．must D．may
答案：C
句意：医生说锻炼对身体重要，但是必须是有规律的锻炼。
解析：考查情态动词。Can一般表示“可能，或能力”；will表示“意志”；may表示“许可，
可能”；must表示“必须”。
7 （2010北京23）
---Good morning. I've got an appointment with Miss Smith in the Personnel
Department.
--Ah, good morning. You ______ be Mrs. Peters.
A. might B. must C. would D. can
答案：B
考点:本题考查情态动词在语境中的运用。
解析：第一个说话人说和史密斯小姐有约，那下面的人就回应说，"那您一定就是Mrs.
Peters了"因此排除A,C.D
8 （2010浙江17）
“You ______ have a wrong number,” she said. “There’s no one of that name here.”
A. need B. can
C. must D. would
答案：C
9 (09湖南30)
— It’s the office! So you ______ know eating is not allowed here.
— Oh, sorry.
A. must B. will C. may D. need
答案A
解析 句意为：这是办公室！因此你必须知道吃的不允许带到这里。must表示“绝不”的意思
10 (09上海27)
It _____ have been Tom that parked the car here, as he is the only one with a car.
A. may B. can C. must D. should
答案 C
11 (09重庆32)
—Hi, Tom. Any idea where Jane is?
—She _____ in the classroom. I saw her there just now.
A. shall be B. should have been C. must be D. might have been
答案C
12 .(07上海29)
—Guess what？ I have got A for my term paper.
—Great!You ______ read widely and put a lot of work into it.
A.must B.should C.must have D.should have
答案 C
解析 由“have got A”可知是对过去发生事情的推测，故用“情态动词+have done”结构。must have done表示“必定做过某事”，符合题意。
13 .(07安徽23)
The teacher ______ have thought Johnson was worth it or she wouldn’t have wasted time on him， I suppose.
A.should B.can C.would D.must
答案 D
解析 must have done表示对过去所做事情的肯定判断，表示“一定……”。
14 .(06浙江19)
— Could I have a word with you，mum?
— Oh dear，if you ______.
A.can B.must C.may D.should
答案 B
解析 考查情态动词的用法。句意为：妈妈，我可以和你说句话吗？”“噢，亲爱的，如果你非要说的话。”must表示必须要做的事。
15 .(05全国Ⅰ26)
Tom，you ______ leave all your clothes on the floor like this!
A.wouldn’t B.mustn’t C.needn’t D.may not
答案 B
解析 考查情态动词。wouldn’t用以提示客气的请求；mustn’t表示禁止，不允许；needn’t表示没必要；may not表示不可以。根据语境要求Tom不许把衣服放在地板上。
16 .(05全国Ⅲ19)
John，look at the time. ______ you play the piano at such a late hour?
A.Must B.Can C.May D.Need
答案 A
解析 must在此处显示出说话人的不快，有“难道非要”的意思。
17 .(05北京26)
He ______ have completed his work；otherwise，he wouldn’t be enjoying himself by the seaside.
A.should B.mustC.wouldn’t D.can’t
答案 B
解析 考查情态动词表猜测的用法。由句意 “他一定是已经完成工作了；否则，他就不会在海边玩得那么高兴。”可知是对过去发生事情的肯定推测。
18 .(07江苏22)
—She looks very happy.She ______ have passed the exam.
—I guess so.It’s not difficult after all.
A.should B.could C.must D.might
答案 C
解析 must have passed the exam肯定是通过考试了，由前句中的“happy”和下句中的“not difficult after all”
可以推知。
19 .(06广东22)
— Must he come to sign this paper himself?
— Yes，he ______.
A.need B.mustC.may D.will
答案 B
解析 表示要求时，肯定回答用must， 否定用needn’t。
20 .(05重庆33)
I was on the highway when this car went past followed by a police car.They ______ at least 150 kilometers an hour.
A.should have been doing B.must have been doing
C.could have done D.would have done
答案 B
解析 must have done用于肯定句中，表示对过去事情的推测，意为“想必是，一定是”。否定句、疑问句中对过去情况的推测，要用can/could have done的形式。
21 .(05江西22)
—Tom is never late for work.Why is he absent today?
—Something ______ to him.
A.must happen B.should have happened
C.could have happened D.must have happened
答案 D
解析 本题考查情态动词的用法。must have done的意思是“一定发生了某事”。由对话所提供的情景可知：汤姆从不迟到，所以他“一定有事”。因此D项正确。
.(04上海28)
Children under 12 years of age in that country ______ be under adnlt’s supervision when in a public library.
A. must B.may C.can D.need
答案 A
解析 句意为：未满12岁的儿童必须在成人的监督下呆在图书馆。表示“必须”时用must侧重主观，have to侧重客观。
（素心守拙整理）
评论