资源简介

第8章 情态动词
情态动词是表示表示说话人的情绪，态度或语气等的动词，不能单独做谓语，只能和其他动词原形构成谓语。
can只能用于一般现在时和一般过去式 (could) ，没有人称和数的变化。be able to可用于各种时态，有人称和数的变化。
can可以表示①能力；②请求，许可；③可能性或推测
Jane can drive car.
Can I borrow your umbrella
That can’t be Mary. She has gone abroad.
Could I use your cell phone for a while (语气委婉)
may可以表示①请求许可；②允许；③推测 (可能性较小)
might比may的语气更加委婉一些。也可做may的过去式。
May I use your name and address
You may go now.
It may rain the day after tomorrow.
He asked if he might go home.
must可以表示①必须；②推测；have to表示“，必须，不得不”强调客观，must多强调主观
All passengers must wear seat belts.
This book mustn’t be removed from the library. (禁止）
It must be John’s. It has his name on it. （推测））
need可以表示①作情态动词; ②作实义动词
There’s enough time for you to go to the airport. You needn’t hurry up. (安徽中考)
I don’t need to buy a new backpack. = I needn’t buy a new backpack.
--Need I answer the question
--Yes, you must/have to.
--No, you needn’t.
should可以表示①应该；②推测；
We should protect the environment.
She left hours ago. She should be home now.
表示最好，缩写为 ’d better
You’d better eat these bananas before they go bad.

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