2015情态动词表推测的讲解及练习题.doc

表推测时，英语中只使用must,may,might,may not和can't。这五个表达的语气依次递减：
must:一定（语气肯定） 可能性最大
may might ； can could 可能 不确定 可能性不大
may not：也许不（表否定）
can't：一定不；不可能（must的反义） 可能性为零
推测现在的事情用must,may,might,may not和can't+do或be
e.g.She must be at home now. The boy may play now.
推测过去的事情用must,may,might,may not和can't+have done
e.g.She might have been ill yesterday. He must have hold the party.
情态动词must, can, could, may, might表推测的用法
情态动词中的must, can, could, may, might都表推测。其中must的可能性最大，can / could次之，may / might最小。具体用法如下：
1.must的用法
（1）表示推测“可能性”时，意思是“一定、准是”，语气较肯定，较有把握。
He must be American. = It is certain that he is American. 他准是个美国人。
（2）must表推测只能用于肯定句。如果要表示“一定不、肯定不”的意思时，应用can’t,如询问某种可能时，应用can。
He must know my address. 他肯定知道我的地址。（一定）
He can’t know my address. 他肯定不知道我的地址。（一定不）
Can he know my address? 他知道我的地址吗？（询问可能性）
（3）must表示推测时，可以推测现在/正在发生的动作/过去发生的动作。
He must have a car now. （现在）他一定有辆小汽车。
He must be doing his exercises in the classroom.（正在进行）他一定在教室里做练习。
He must have finished the work.（过去发生）他一定已完成了工作。
注：must表示推测时很少用于将来的情况。一般不用He must come tomorrow.可用It`s certain / I’m sure that he will come tomorrow.
（4）在反意疑问句中，当附属部分含有表示推测意义的must时，疑问部分的助动词应与must后面的动词在非推测情况下的用法保持一致。
He must be a worker, isn’t he? （现在）他准是个工人，是吗？
It must have rained last night, didn’t it? （过去）昨晚一定下雨了，是不是？
You must have learned English for many years, haven’t you? （完成时）你一定学了好多年英语，是吗？
2.can / could的用法
（1）can表示推测“可能性”时，往往用于否定句或疑问句。Can’t“一定不”，语气很肯定。can在疑问句中意思是“会、可能”。用于肯定句时，表示理论上的，潜在的可能性（有倾向，实际上未必会发生或者不涉及实际是否发生）往往与sometimes 或者 someone 有关。
Accidents can happen.
He can’t be at home. = It is impossible that he is at home. 他一定不在家。
（2）can /can’t后可接进行时/完成时，表示对现在发生的动作或过去发生的动作进行推测。
They can’t be reading in the library. 他们一定不在图书馆读书。
He can’t have gone to Shanghai for I saw him a minute ago.
他不可能去了上海，我刚才还看见他。
It’s so late. Where can she have gone? 天晚了，她可能去哪儿了呢？
（3）在反意疑问句中，当陈述部分含有表示推测意义的can’t时，疑问部分的助动词应与can’t后面的动词在非推测情况下的用法保持一致.
He can’t be a teacher, is he? 他不是教师，是吗？
She can’t have finished her homework, has she? 她一定没有完成家庭作业，是不是？
could可用于表示某事有可能发生表示可能性不大的推测。意思相当于may/might
Don’t eat it. It could be poisonous. 不要吃它，可能有毒。
The plane could be delayed by fog. 飞机可能会因为雾晚点。
（5）could还可以用于表示客气、委婉、礼貌的请求语气。
Excuse me, could you tell me the way to the bus station?
Could you help me?
（6）couldn’t表示否定推测，表示某事不可能真实，或由于特定事实或环境某事肯定不会发生。
It couldn’t possibly be poison. 这不可能是毒药。
表示对过去发生的事推测，常常和have done 连用
He was not at home last night . He could/ might have gone to movies.
I didn't see her at the meeting yesterday; she couldn't have spoken at the meeting.
3. may和might的用法
（1）may, might表示推测“可能性”时，意思是“可能”、“也许”，语气没有 must肯定。
He may / might be American. = It is possible that he is American.
他可能是个美国人。
注：might不表示过去时态，只是语气上比may更委婉，表示的可能性更小。
（2）may, might表推测时，可以用于否定句，意思是“可能不、也许不”，但不用于疑问句。
He may / might not be at home. 他也许不在家。
（3）may, might可以推测现在正在发生的动作或过去发生的动作。
He may / might be sleeping now. （现在）他可能正在睡觉。
The boy may / might not be watching TV at home. （现在）
这个男孩可能没在家看电视
These students may / might have seen the film before.（过去）
这些学生以前可能看过这部电影。
（4）may, might还可以推测将来的情况。
I think we should take raincoat with us, it may rain.
我想我们应该带上雨衣，可能要下雨了。
She might not come this afternoon. 她今天下午可能不来

一、单项选择
1 John___ come to see us tonight, but he isn't very sure yet.
A. may B. need C. can’t D. must
2 John isn’t in the classroom. He _______ play soccer on the playground with Bob.
A. can B. must C. should D. can’t
3 That _______not be her husband . She is still single.
A. may B.can C. could D. might
4 You___ go and see a doctor at once because you got a fever.
A. can B. must C. dare D. would
5 -Can you speak Japanese? -No, I____.
A. mustn't B. can't C. needn't D. may not
6 -He___ be in the classroom, I think.
-No, he ___ be in the classroom. I saw him go home a minute ago.
can; may not B. must; may not C. may; can't D. may; mustn't
7 -Is Lena swimming in the pool?
-No, she swim. She is terrified of water.
A. may not B. must not C. can't D. needn't
8 He isn't at school. I think he ___ be ill.
A. can B. shall C. must D. might
9 -What do you think “upset” means?
- I’m not sure. It mean “sad”.
may B. must C. can D. should
10 The children___ play football on the road.
can't B. can
C. mustn't D. must
11.The road is wet . It ______last night.
A must rain B must have rained
C could have rained D can have rained
He ______you more help , even though he was busy .
A might have given B might not give
C may not have given D may give

答案 ABBBB CCDAA BA