All 5 children of the Blacks are now working abroad will come back for their parents’

问题补充：

All 5 children of the Blacks, are now working abroad, will come back for their parents’ 50th wedding anniversary.

A. two of whom

B. two of them

C. both of whom

D. both of them

答案：

(答案→)A. two of whom

B. two of them

C. both of whom

D. both of them

解析：考查定语从句。根据题中逗号，可知考查非限定性定语从句，根据句意5个孩子中的两个孩子，故选A。