The old man has two sons is a soldier.A. one of whomB. both of themC. all of whomD. both o

问题补充：

The old man has two sons，is a soldier.

A. one of whom

B. both of them

C. all of whom

D. both of whom

答案：

(答案→)A. one of whom

B. both of them

C. all of whom

D. both of whom

解析：考查定语从句。那个老人有俩个儿子，都是医生。 根据前句two，是两者，而all是三者或三者以上，排除C， 根据谓语动词是is，B和C都是both，做主语谓语动词是复数，再有B中them也不对，需要有连词，排除B和C，根据谓语动词is单数，所以主语必须是单数，所以A正确