We’ll put off the picnic until next week,when (=by then) the weather may be better.请问这句话为什么when 可以用by then?

问题描述:

We’ll put off the picnic until next week,when (=by then) the weather may be better.请问这句话为什么when 可以用by then?

when (=by then) the weather may be better是非限制性定语从句,修饰week.关系副词when在从句里面作时间状语.by then也是时间状语,所以when相当于by then.但这里其实不可以换成by then的,要换成and by then.如果只简...我已经说了,when 引导的是定语从句,当然不要and了。只有两个并列分句才要用and。