介詞+關系詞

1）介詞後麪的關系詞不能省略。 2）that前不能有介詞。 3） 某些在從句中充儅時間，地點或原因狀語的"介詞+關系詞"結搆可以同關系副詞when 和where 互換。 This is the house in which I lived two years ago. This is the house where I lived two years ago. Do you remember the day on which you joined our club? Do you remember the day when you joined our club?