英语小小问题

题目

英语小小问题
Mark was a student at this university from 1990 to 1995,during which time he studied hard.为什么during后面用which?
After the war,a new school building was put up where there had once been a theatre.这里 where there had once been a theatre.there有什么作用,去掉可不可以?此句可不可以改为这样After the war,a new school building was put up there where had once been a theatre.

答案

He studied hard during the time (from 1990 to 1995).
在从句里面,1990 to 1995是做during的宾语啊
当然用which
这个there是there be句型（这个是过去完成时的There be）,当然不能去掉
不可以变成你这样