On the top of the hill we may see that the clouds ------

题目

On the top of the hill we may see that the clouds ------
A.are building up B.are built up
C.are building D.are built
请写出理由，

答案

A哦.
clouds are building up 就是描写云在聚集,与前面的that在一起做从句,是see的宾语.