可以省略 只要后面不接宾语或其他的都可以省略
第一种情况:如:Zoos are terrible places for animals to live(in zoos.)
如果加上了in 必然要加上zoos 如果把它们都加上了 语句就会变得很累赘。
第二种情况:where 是副词 副词遇到介词是可以省略。
就像你刚才说的,Where是关系副词,所以可以说where这个词引导从句的时候后面就不用再加介词了,但是如果是which或者that就要加介词
This is the room where I lived
= This is the room which I lived in
= This is the room in which I lived
= This is the room that I lived in
可以理解为,where这个字当中已经包括了介词的概念
你这个情况可以省略.