分类：教育/科学-外语学习-英语考试
问题：Wemusttakemeasurestopreventourea? 
We must ta measures to prevent our earth( ).A.to be polluted B.from pollutingC.from being polluted D.from pollutedＣ和Ｄ有什么区别？
回答：C 
介词后不可能直接加过去分词.