the play was put on by the hospital which i was born inthe play was put on by the hospital( ) i was born in.为什么这里要填which,而不能填where啊?

the play was put on by the hospital which i was born in
the play was put on by the hospital( ) i was born in.
为什么这里要填which,而不能填where啊?

因为后面有个in
有介词说明指代的是名词,用which
如果后面的in去掉,那么就用where