He is the only one of the students who a winner of a scholarship for three years.A. isB. a

问题补充：

He is the only one of the students who a winner of a scholarship for three years.

A. is

B. are

C. have been

D. has been

答案：

A. is

B. are

C. have been

(答案→)D. has been

解析：考察主谓一致和时态。本题中定语从句的先行词是the only one，而不是the students，关系代词who指代先行词在句中作主语，故谓语动词要和the only one保持一致，故使用单数形式。句意：他是三年以来学生中唯一的一个赢得奖学金的人。根据后面的时间状语for three years，说明使用现在完成时的时态。故D正确。