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

问题补充：

He is the only one of the students who a winner of 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：根据for three years，故用现在完成时，且这个定语从句的先行词是the only one of the students，故谓语动词用单数，所以选D。