题目内容：

There are two small rooms in the house ,_______served as a bathroom.
A the smaller of which B the smaller of them
C the smallest of which D the smallest of that

优质解答

选B.首先 是有两个房子,不是三个或三个以上,所以不用最高级,排除C、D.然后后面的served 被当作被用于 却没有谓语动词构成被动,所以没有谓动的定语从句带有自己的主语称为逻辑主语,而which是关系代词不能做主语,所以用them