Her sister left home in1998, and since.
A. had not been heard of
B. has not been heard of
C. had not heard of
D. has been 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 been heard of
解析：考查时态。根据本句中的副词since可知使用现在完成时，句意;他姐姐在1998年离开了家，从那以后就再也没有被听说过。根据句意说明使用否定句，故B正确。