they ( ) (go) before we saw them.
问题描述：
they ( ) (go) before we saw them.
they ) (go) before we saw them.
答
they【had gone】 before we saw them.
在我们看到他们之前,他们就已经离开了.
考察：过去完成时
注意时间状语是：before we saw them,这里的时间是：过去的过去!所以应该是过去完成时