He left here for Beijing in 1998 I have heard nothing from her.A. since thenB. since when

问题补充：

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

答案：

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。