This is the apartment .We used to live in this apartment 合并
问题描述：
This is the apartment .We used to live in this apartment 合并
定语从句
答
这是定语从句,引导词代替了先行词在从句中充当地点状语
This is the apartment in which we used to live.
This is the aprtment where we used to live.
This is the apartment that we used to live.