we must polluted water entering the clean river.

分类: 作业答案 • 2022-01-09 18:03:03

问题描述：

we must __polluted water__ entering the clean river.
prevented,from 和keep ,from选那一个呀?

答

prevented,from和 keep ,from都有阻止...不被怎么样
可是按照句子应该是选择keep from,原因就是时态了,we must .must 是情态动词,后不能接过去式的

we must __polluted water__ entering the clean river.