下列属于人畜共患寄生虫病的是（）。

A.炭疽

B.旋毛虫病

C.口蹄疫

D.猪瘟

E.结核

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