he has two sons,( )work as doctors.Aboth of which Bboth of whom Cboth of which Dall of whom

Question

选哪一个？为什么？

Answer 1

他有两个儿子，都是医生。
B both，复数，不能后接which。all的话应该是all of them

Answer 2

B
of表示同位关系：即用于在A+of+B结构，其中的A和B为同位关系。如：
Her sons, both of whom work abroad, ring her up every week. 她的两个儿子，都在国外工作，他们每周都给她打电话来。本回答被提问者采纳

Answer 3

A