It was at 9 o'clock that he came back和It was 9 o'clock which he came back为什么分别that和which
问题描述：
It was at 9 o'clock that he came back和It was 9 o'clock which he came back为什么分别that和which
答
当主语It was at 9 o'clock 中有at时，后面的连接词只能是that
而第二句没有at，可以用 which和when，但因为后面的从句不是表示时间的，所以用which
(这个语法点我是有把握的，所以你大可放心使用)
答
第二句应该用when吧。
答
It was at 9 o'clock that he came back.这里It was……that……是一个强调句,只是一个句型.可以转换为He came backat 9 o'clock.It was 9 o'clock which he came back里which 是 因为 9 o'clock 引导 出一个 定语从...