both of them与both of whom

题目

both of them与both of whom
1.Both of them are teachers.与
2.He has two sons,both of whom are teachers.
请问第2句中的whom可以用them代替吗.为啥呢
如果你知道为什么的话请说具体一些，骗人骗到底~

答案

不可.如果改成them,那么both of them are teachers就是一句完整句子,一个逗号是不可连接两个句子的,如果改为He has two sons and both of them are teachers.就可以了.