在这里是haven't 还是hadn't?
——Have you heard from Mr Black recently?
—— No, we ____ each other since he went to abroad.
A. didn't write B.haven't written C.wouldn't write D.hadn't written
答案是B 我选到D去了 这个知识点我一直理解得很模糊.
是have还是had呢?
解释一下,谢谢!