He left here for Beijing in 1998 , I have heard nothing from her.
A. since then
B. since when
C. from then on
D. after that
网友回答
A. since then
(答案→)B. since when
C. from then on
D. after that
解析：考查定语从句：句意：他在1998年离开这儿去了北京，之后我一直没有他的消息。从现在完成时判断是AB选项，因为两句话之间没有连词，所以是定语从句，A不能引导定语从句，since when能引导定语从句，故答案为B。