选择I Can't find book,Who( took it away)?为什么填它?

问题描述:

选择I Can't find book,Who( took it away)?为什么填它?
.而不填did take it away

为什么要用一个do动词呢?
实际的take代替了句型中的do.
类似的,就好象Be动词一样
比如某些情况下可以说
be yours
但如果涉及到具体某人或某物
It is yours
用is代替了be