Question

定语从句~The old woman has two sons,one _____ is a teacher.

A.of who B.of whom C.of which D.of them
请给出答案并解释，另外我选的D，为什么错？

Answer 1

是 one of whom.

One of them 也可以但要分两句的

The old woman has two sons. One of them is a teacher.

一句的话

The old woman has two sons, one of whom is a teacher.

Answer 2

此题考查非限制性定语从句，先行词为two sons ，指人，故排除C。介词不能加who排除A。
如果把此句改成The old woman has two sons and one _____ is a teacher .就应选D。
即有连词用人称代词无连词用关系代词。
此题前后两句之间无连词，故用关系代词而不用人称代词

Answer 3

答案：C
which指代上面的two sons,英语中两个独立的句子不能用逗号连接，而选D的话则不再是定语从句，而是独立的两句话