怎样判断 定语从句中的状语成分？

Question

This is the murder case_______ the police are looking into (that/which)
This is often the case _______students recognize every word but can't figure(in which/where)

I never forgot the day _______ I devote to taking care of the old people on March 15(that/which)
I never forget the day_______ I stay in the Ghost house (when/on which)

老师说过当case在定语从句中作状语时，常用where 或in which引导定语从句，问题是怎么判断在定语从句中充当状语成分，如例句为什么第一个是which 第二个是where?

Answer 1

第一句里面，先行词case是做look into的宾语，所以用which。
第二句话是作状语，所以用where

Answer 2

这里做名词，用which从句作定语