He left the knife ___he had found itA after B before C where D as为什么要用where 不用 after?

问题描述:

He left the knife ___he had found it
A after B before C where D as
为什么要用where 不用 after?

where 引导地点状语从句,修饰前面的knife.after表示在...之后,不能引导从句.
句意是:他把刀放回到了他拾起的那个地方.