She wrote a month ago, we’ve heard nothing.A. since when B. before whichC. since

She wrote a month ago, ______ we’ve heard nothing.

A. since when B. before whichC. since thatD. after which

试题答案

【答案】

A

【解析】

此题答案选A，其中when 相当于 a month ago。若改为 and since then 也不可以。