江西成人高考2022英语语法精讲could的用法

　  1)表过去的可能和许可，（多用于间接引语中）

　　At that time we thought the story could not be true.

　　那时我们认为所说的事不可能是真的。

　　Father said I could swim in the river.

　　爸爸说我可以在河里游泳。

　　2)表过去的能力

　　I could swim when I was only six.

　　我刚六岁就能游泳。

　　Could在肯定句中表示过去的能力时，常表抽象的一般的能力。

　　He could be very naughty when he was a child.

　　他小时候会是很顽皮的。

　　3)表“允许”。可表示委婉客气的提出问题或陈述看法

　　Could I use your bike?

　　Yes, you can.

　　他会记得那时吗?

　　I’m afraid I couldn’t give you an answer today.

　　恐怕我今天不能回答你。

　　The teacher said you could go to the store for sweets.

　　老师说你可以去商店买糖。

　　3)Could/can+have done 结构表示对过去发生的事情的“怀疑”或“不肯定”。 could 加完成式还用于肯定句时一般表过去可能完成而却未完成的动作。

　　Can they have won the basketball match？

　　他们赢了那场篮球赛吗？

　　What you referred to just now can have made her very sad.

　　你刚刚所谈到的可能令他很伤心。

　　You could have completed the task a little earlier.

　　你本来能早点完成任务的。（但事实上并没有提前完成任务）

　　I could have passed my examination easily but I made too many stupid mistakes.

　　我本可以轻易通过考试，但我犯了太多不该犯的错误。

　　如表具体做某一件事的能力时，则须用 be able to .

　　He was able to translate the article without a dictionary.

　　他可以不用词典翻译那篇文章。

　　Can表示一贯的能力 ，be able to表示客观能力和通过努力可以达到的能力

　　I can’t swim. But I am sure I will be able to swim through more practicing.

　　The fire spread through the hotel, but everyone was able to get out

　　When the boat sank he was able to swim to the bank