We couldn't watch until our homework was finished.为什么用couldn't 换成cann't 行不行 could 和 can 有什么区别?

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/29 13:18:19
We couldn't watch until our homework was finished.为什么用couldn't 换成cann't 行不行 could 和 can 有什么区别?
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We couldn't watch until our homework was finished.为什么用couldn't 换成cann't 行不行 could 和 can 有什么区别?
We couldn't watch until our homework was finished.
为什么用couldn't 换成cann't 行不行 could 和 can 有什么区别?

We couldn't watch until our homework was finished.为什么用couldn't 换成cann't 行不行 could 和 can 有什么区别?
区别在于语气和事态两种情况
语气上couldn't比can't委婉点 客气点
时态上couldn't是can't的过去形式
你是句话属于后者 因为后面有was 所以为了时态一致要用couldn't

前后时态要一致,不能换,因为从句用WAS ,所以要用过去时COULDN‘T

不可以,以为后面是was,前后事态要一致。
意思为能,可以的时候,could是can的过去式。意思为可能的时候,没有太大区别,could的可能性比can小

can 一般是说能力 比如说我不会游泳就是can't 或者说我会做饭就是can
could 这里是说无法,但是这个能力不是本身的,是因为外界的(没有写完作业) can 是本身的能力

这是一个时间状语从句!主句跟从句的时间状语必须一致!后面的是was前面的当然只能是can的过去式啊!所以couldn't是不可以换成cann't的!

could是过去式里用的,过去式里不能用cant.
could 在假设语态里也要用到,例如
i could have done my homework last night. 意思就是我其实可以在昨天晚上完成作业。