His sister left home in 1998,and since .
A. had not been heard of
B. has not been heard of
C. had not heard of
D. has not heard of
网友回答
A. had not been heard of
(答案→)B. has not been heard of
C. had not heard of
D. has not heard of
解析：考察时态与语态。根据关键词since可知与完成时连用，且根据句意可知是被动语态。句意：他的妹妹在1998年离开家，从那以后就再也没有被听说过。故B正确。