when表突然意思时候的几个固定用法
问题描述：
when表突然意思时候的几个固定用法
好像有be about to do.when 还有我就想不起来啦 多谢大家帮帮忙
答
通常主句为过去进行时,从句为一般过去时
如
i was having my dinner when there was a sudden
knock at the dorr