文档介绍：零起点大学英语基础教程
Unit 2
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Reading Aloud
Life Is Full of Steam
Chew, chew, chew your bread
Gently down the can use my dictionary.
允许
The airliner can fly the Atlantic.
客观能力
He can't write in English.
能力
The passengers can't leave London this evening.
客观能力
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二、 may, might
1) 表示请求和允许。
might比 may语气更委婉，而不是过去式。否定回答时可用can’t或mustn’t，表示“不可以，禁止”。
--Might/ May I smoke in this room?
-- No, you mustn’t.
-- May/Might I take this book out of the room?
-- Yes, you can. (No, you can’t / mustn’t. )
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2）用于祈使句，表示祝愿。
May you succeed!
3) 表示推测、可能性（不用于疑问句）。
might不是过去式，它所表示的可能性比may小。
1．He may /might be very busy now.
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2. They may come tomorrow.
推测可能性
He may call me this evening.
推测可能性
It may be very hot this summer.
推测可能性
She may be in the bookstore now.
推测可能性
You may do your homework tomorrow.
允许
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三、 must, have to
1) 表示必须、必要。
You must come in time.
在回答引出的问句时，如果是否定的，不能用mustn’t（禁止，不准），而用needn’t, don’t have to（不必）.
-- Must we hand in our exercise books today?
-- Yes, you must.
-- No, you don’t have to / you needn’t.
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2) must是说话人的主观看法，而have to则强调客观需要。Must只有一般现在时， have to 有更多的时态形式。
The play isn’t interesting, I really must go now.
I had to work when I was your age.
3) 表示推测、可能性（只用于肯定的陈述句）
You’re Tom’s good friend, so you must know what he likes best.
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3. Pilots must adjust to constant changes in time.
必须
We must get to London before 7 .
主观看法
You must stay at home all day.
必须
The doctor must be in the office now.
推测
The man with a hat must be Tom.
推测
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四、 should
1) should表示“应该”。
I should help her because she is in trouble.
2) 表示劝告、建议和命令。
You should go to class right away.
Should I open the window?
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3) 表示推测
should (客观推测), must(主观推测)。
　
must be home by now. (断定他已到家)
ought should be home by now.(不太肯定)
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5. You should tell him abou