Jack must have been joking when he said that he was going to quit his job.为什么用when用what不行吗
问题描述：
Jack must have been joking when he said that he was going to quit his job.
为什么用when用what不行吗
答
时间状语从句
不能用what 代替
答
当他说他要辞职的时候,一定是在开玩笑.
你要整个句子一起读.When是独立的.当……时,
而what he said就讲不通了.