问题补充：
His uncle went abroad in , and since.
A. has not been heard of
B. had not been heard of
C. had not heard of
D. has not heard of
答案：
(答案→)A. has not been heard of
B. had not been heard of
C. had not heard of
D. has not heard of
解析：考查时态和语态。Since后跟过去时间，句子用现在完成时态。而且His uncle和hear之间是动宾关系，所以用被动语态。选A。
