He has two children,both of ______ being abroad.A.them B.whi

这个问题,我给你举三个例子
He has two children,both of ______ being abroad.
He has two children,both of ______are abroad
He has two children,and both of _____are abroad
A.them B.which C.whom D.who
这三个题的正确答案分别是：ACA
我明白你的想法是为什么你问的问题后面不是非限定性定语从句,现在看看,第二个句子才是非限定性定语从句,对比两个句子的区别,就在于第一个那个系动词是be——are,是一个完整的句子.而你给的是being,这是非谓语,那么both of them就是后面的逻辑主语,整个both of them being abroad不是短语.
顺便再给你第三个,这也是一种情况,and表示并列的两个完整的句子,而不是从句,所以也是both of them

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