前置詞を伴う関係代名詞

＜１＞２つの文章がある。
This is the desk. There were many books on the desk.

＜２＞２つの文章をくっつける時。
This is the desk there were many books on which

※２つ目の分のonの後のthe deskをwhichに変える。

＜３＞
①whichに変えたら、whichを間に持ってくる。その時、onも一緒に持ってくる場合が多い。
This is the desk on which there were many books.

②whichに変えたらwhichだけを間に持ってきて、onは残したままの場合もある。
This is the desk which there were many books on.

※ただし、②の場合は、whichがthatに代わることが多い。