［定語從句］介詞+關(guān)系詞
1）介詞后面的關(guān)系詞不能省略。
2）that前不能有介詞。
3）某些在從句中充當(dāng)時(shí)間，地點(diǎn)或原因狀語的介詞+關(guān)系詞結(jié)構(gòu)可以同關(guān)系副詞when 和where 互換。例如：
This is the house in which I lived two years ago. 這是我兩年前住過的房子。
This is the house where I lived two years ago.
Do you remember the day on which you joined our club？ 還記得你加入我們俱樂部的那一天嗎？
Do you remember the day when you joined our club？
