1.can/could都属于情态动词，
本身有各种意义，具体在句子中不同。
2.情态动词不能单独作谓语，
只能和动词一起构成谓语。
3.情态动词没有人称和数量的变化。
4.表示说话人的语气和情感。
Can/could的几种句式：
肯定句 否定句 缩略式
can can not can’t
could could not couldn’t
疑问句：
can you…….?
could you…...?
Can/could用法共同点：
1.都表示具备的能力，指现在、过去无论什么时候想做就能做到的能力。
Could表示过去的能力，can表示现在或将来的能力。
2.在否定句和疑问句中，都表示猜测语气。Can表示猜测的可能性要多些，
而could表示猜测的可能性要小、轻些。
3.都可以表示建议和请求，
can表示肯定，could的请求语气更委婉。
Can与could用法不同点：
1.can的语气肯定，could语气比较委婉。
2.can通常用在表示现在的事 情，
3.could用在表示过去的事情。
4.当表示允许别人做某事时，
用can而不用could.
一、判断下列句子的用法：
1.A hen can’t swim.
2.How can that be true?
3.Could you pass the paper to me?
4.I couldn’t play the piano until I was fifteen years old.
5.What you said couldn’t be true.
6.Can I take this seat?
7.Could I use your phone?
8.Yes,of course you can.
二、选择题
1. At that time we thought the story_____ not be true.
A)could B)must C)can
2. You___ the work better in the future.
A)could did B)can do C)could do
3.The room is dirty; it ____cleaned.
A) can‘t be B) couldn’t be
C) mustn't be
4.Mary ____my letter, because she is worring about it now.
A) should receive B) can’t receive
C) couldn't receive
5.An Englishman who ____not speak Chinese in China.
A) must B) could C) can
6.Mr Wang ______ write last year, he was ill for three years.
A. mustn’t B. couldn’t C. can’t
7. –Who is the man over there? Is it Mr Li?
--No, it ______ be him. Mr Li is much taller.
A. mustn’t B. could not C. can’t
8.Could I seat here?
Yes, of course you _______.
A. can B.could C.must
三、按要求完成句子
1. He can ride a bike. （改一般疑问句和否定句，并作肯定和否定回答）
一般疑问句_________________________________________
否定句_________________________________________
肯定回答______________否定回答______________
2.你会弹吉他吗？
_____ you _____ ______ guitar?
3.两年前我不会骑自行车。
I ______ ______a bike two years ______.
四、下列各句均有一处错误，请指出并改正
1.He can speaks English very well.
A B C D
2.Can you play a piano?
A B C D
3.He doesn’t buy something his brother.
A B C D
4.I couldn’t speak Japanese when I am four.
A B C D
5.What can you sister does?
A B C D
