介词加where?可不可以?

题目

介词加where?可不可以?
高中语法题The man was standing behind the window,_____ he could see what was happening outside the house.
A.from which B.from where C.where D.which
两本书上一本选C,一本选B.
那个是正确答案？
我知道where前不能加介词，但是he could see what was happening outside the house standing behind the window不通
那到底要不要加from 有from才通啊

答案

本题答案为 B.from where .
from where 引导非限制性定语从句,其先行词是以地点名词the window为中心的前面的一句话.意指 from the place wherethe man was standing.
当先行词是以地点名词或者时间名词为中心的一句话时,定语从句由“介词+where”或者“介词+when”.其中,when=which place,when=which time.
当先行词是地点名词或者时间名词,并且,它们作介词宾语在定语从句中作地点或者时间状语时,定语从句由where或者when引导,相当于“介词+which”.
比较：
① He stood at the window,____ he could see what was happening.
A.from where B.from which C.which D.at which、
② The southern states wanted to set up a country of their own,where/in which they would be free to keep black slaves．