Jack has three sons and both of are studying in China.A. themB. thatC. whomD. who

问题补充：

Jack has three sons, and both of are studying in China.

A. them

B. that

C. whom

D. who

答案：

(答案→)A. them

B. that

C. whom

D. who

解析：本题的含义是杰克有三个儿子，他们中有两位正在中国学习，them表示他们的含义，故本题选A。