Jack must have been joking when he said that he was going to quit his job.
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
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.