could语法

1. 用于提出要求或请求

句型：Could you please...?

Could you please take out the rubbish？

肯定回答：

Yes, sure/Of course./No problem./With pleasure./Of course/Certainly, I can. 

否定回答：

Sorry, I can't. I have to.../ Sorry, I'm going to .../ I'm afraid I can't.

2. 用于征询许可

“Could I...?” 意为 “我能……吗？”，用于请求对方允许自己做某事。

Could I go out for dinner with my friends?

对别人的请求许可的回答，

一般只用can ，而不用 could. 

3.could 表示“能力”,是can 的过去式，译为“可以；能够”表示“过去的能力”,没有人称和数的变化。

She could read at the age of four. （肯定句）

I could not swim when I was young. （否定句）

-Could you swim when you were young?（一般疑问句） 

-Yes, I could./No, I couldn't.

What could she do when she was young?(特殊疑问句)

4.表示推测，表推测时could 不是can的过去式，只是语气更委婉-针对现在情况的推测用could+动词原形， couldn’t 表示不可能; 推测已经发生的事或过去的情况用could have done

Today is Sunday. He couldn’t be at school.

Mike couldn’t have found his car, for he came to work by bus this morning.

上期答案：Neither；both; Neither/ None