问题补充:
The pen he is writing is mine.
A. with which
B. in which
C. on which
D. by which
答案:
(答案→)A. with which
B. in which
C. on which
D. by which
解析:. with which是介词+关系代词结构,常用来引导定语从句.with有用的意思,介词之后只能用which,不能用that. with which在定语从句中作状语,即he is writing with a pen.