can的过去式怎么写

could，用于can的过去时;(询问是否可做某事)能，可以;(礼貌地请求别人做事)能。

例句

I could do it now, if you like.

如果你愿意的话，我现在就可以做这事。

he operation could prolong his life by two or three years.

这次手术可使他多活两三年。

only with a few people could she be her real self.

只有和几个人在一起时，她才能表现出真实的自我。

Could you forward any mail to us in New York?

你能不能把所有信件转寄到纽约给我们？

They could not ensure a smooth transfer of political power.

他们无法保证政权的顺利交接。

I could come next week, or the week after.

我可能下周来，或者再下一周。