we must do everything we can ( ) waste water from running into the rivers.

问题描述:

we must do everything we can ( ) waste water from running into the rivers.
A.keep B.kept C.to keep D.keeping
要说明理由,

很显然是 C 啦 to keep 表目的状语啦
我们必须做我们能为能够做的一切 来防止水土流失
“防止水土流失”是目的啦