（1）of which 和 of them的区别主要在于：of which是在从句中.即前面一句是主句,后面也是一个句子,但是两个句子之间不是句号而是逗号.逗号后面接of which.用of which引导的后面的句子是非限制性定语从句.可以是some of which,many of which,one of which等.而后者则是两个句子.第二个句子可以为many of them,some of them,one of them等.后面紧接的就是谓语了.例：I have many books.Some of them are English books.I have many books,one of which is Snow White或者I have many books,of which one is Snow White.
(2)本题应选A.是非限制性定语从句.There were two small rooms in this flat,_____served as the kitchen.
A.the smaller of which B.the small of which C.the smaller of them D.the smaller one
（3）译文：这套房子有两间房.较小的一间是厨房.