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Section ⅢGrammar——情态动词(Ⅰ)
[语境自主领悟]
一、基本特征
1．情态动词有一定的词义，不能单独作谓语，需和实义动词或系动词一起作谓语。The idea that computers can recognize human voices surprises many people. 电脑能识别人的声音，这种想法使很多人感到吃惊。
They must be in the classroom.
他们一定在教室里。
2．情态动词一般无人称和数的变化，个别情态动词有现在时和过去时两种时态变化。Mary can speak three languages.
玛丽会说三种语言。
I could drive a car before I left school.
毕业前我就会开车。
3．构成否定句时，not放在其后面。
My brother can't swim.
我弟弟不会游泳。
4．情态动词后接动词原形。
You will do as I told you.
你得按我说的去做。
He might come tomorrow，but I am not quite sure.
他可能明天来，但我不确定。
[即时训练1]
单句改错
①We should to study hard for our motherland and ourselves.去掉to
②She can sings that song in English.sings→sing
③This book doesn't must be removed from the library.doesn't must→mustn't 二、基本用法
1．can与could的用法
(1)表示能力：can用来表示现在的能力，could表示过去的能力。
I can play basketball now，but I couldn't when I was young.
现在我会打篮球了，但小时候我不会。
(2)表示请求和许可：could语气比can委婉，但回答时只能用can。
Can/Could you lend me a hand?
你能帮我一下吗？
(3)表示推测，意为“可能”。多用于否定句或疑问句。
—Can he be in the reading room now?
—No，he can't be in it.Because I saw him in the office just now.
——他现在可能在阅览室吗？
——不，他不可能在(阅览室)。因为我刚刚在办公室看见他了。
(4)表示理论上或习惯上的可能性，意为“可能会”。
Jogging can be beneficial to the health.
慢跑可能对身体健康有益。
[明辨异同]can，be able to表示“能力”时的区别
婴儿们刚生下来时会游泳。(自身具有的能力)
Without his hard work，he was not able to get good grades.
如果没有他的努力工作，他是不可能取得好成绩的。(经过努力)
[即时训练2]
单句改错
①Sarah didn't believe his explanation and can't forgive him.can't→couldn't
②It mustn't be Peter，for he has gone to Beijing.
mustn't→can't
③You can't never be too careful to cross the road.can't→can或去掉never
【导学号：65162005】2．may/might
(1)表示允许、许可。might在语气上比may更委婉。以may/might开头的问句在否定回答中要用mustn't。
You may choose whatever you like.
你喜欢什么就选择什么。
—May I stay in the room for a while?
我可以在这个房间待一会儿吗？
—Yes，you may./No，you mustn't.
是的，可以。/不，不可以。
(2)表示把握不大的推测，意为“有可能”。用于肯定句或否定句中；might语气更加不肯定。
They may come to attend the meeting，or they may not.他们可能来出席会议，也可能不来。
(3)may和might的其他用法。
①“may＋主语＋动词原形”表示祝愿。
May you have a good time！祝你过得愉快！
May you succeed！祝你成功！
②“may/might as well＋动词原形”表示“不妨，还不如”。
I may/might as well start at once.
我还不如马上就动身。
[即时训练3]
完成句子
①——我能将这本书带出去吗？
—May I take the book out?
——不，你不能。
—No，you mustn't．
②言语不多的人未必就是害羞，他们或许就是安静的人。
Some people who don't like to talk much are not necessarily shy；they may be quiet people．
3．will/would
(1)表示意愿，would是will的过去式。
We will do our best to save the child.
