關於介詞+which在定語從句中的用法，先看一個例子：

This is the house which I was born in.

=This is the house in which I was born.

=This is the house that I was born in.

=This is the house I was born in.

=This is the house where I was born.

可以看出，in which = where，in which中的in也可以放到句子最後。就是說v+prep+地點時，可以用where，代替的就是prep+地點，如果用which，代替的就只是地點，所以在句中仍要用prep ，這樣其實prep+which在定語從句中要確定這個prep用什麼不是固定用法，而是要根據片語靈活搭配，前面舉的例子中，因為是born in sw，所以用in which。你這句中的of which我想也是這樣，因為有include of sth的用法，判斷這個介詞的時候，你就把這個介詞拖到句末去看就是了。

which 用於定語從句，作關係代詞，在句中要做成分

in which 用於定語從句，作關係副詞，在句中不做成分，in which=where

in which 只能用在定語從句中，等於where,在定語從句中作狀語。

如：He lived in the house in which Tom once lived.

He lived in the house where Tom once lived.

定語從句中.如

this is the room in which we stayed

先行詞是room，後的句子是用來修飾room的

但是room不可做stay的成分，因為stay是不及物動詞，後不可直接家賓語

所以要有個介詞．

其實上述的句子＝

this is the room which we stayed in．

這裡的介詞是可以提到which 前的

注意，第二個句子可用that 或省略

但第一個只能用which．只有which前可加介詞 其他介詞的用法也類似於這種!