when和where在定语从句中的用法

When 在定语从句中相当于"介词+先行词"即相当于"介词+which",在从句中做时间状语.
Where 在定语从句中相当于"介词+先行词"即相当于"介词+which",在从句中做地点状语.
如:I will never forget the day when I went to school .
=I will never forget the day on which I went to school .
=I will never forget the day .I went to school first on the day.

This is the house where I lived three years ago.
=This is the house in which I lived three years ago.
=This is the house .I lived in the house three years ago.

when是先行词在从句中做时间状语，where是先行词在从句中做地点状语。