He has two children,both of _______ being abroad.

问题描述:

He has two children,both of _______ being abroad.
A.them B.which C.whom D.who  
为什么是选A呢?

您困惑为什么不选C,是吧?
其实both of _______ being abroad这句中没有谓语动词,也就是说,这不是一个句子,自然也就不能用连词来连接这两部分而B.which C.whom D.who 都是定语从句的连词,都不能选.而且both of _______ being abroad构成独立主格,原则上也需选A.