preposition 後面的what/which/who.

一般學校的英文教who/where/which是句字中指的一樣東西(名詞)
He is the man who stole he car
I know where he lives.
People go the amusement park which provides fun games.
等都是前面說到單一的固定物品而後面補充或附上額外形容資料等的寫法。

但文學或寫作時有時前面所說的未必是單一物品，而是一種狀態或程序或處境或假設等等多元性或綜合性時，便會用多一個preposition加conjunction以表達總括前面全部再引伸後面附加的形容。句子的結構跟簡單的who/where/which差不多，只是意識上作一點停頓讓人可以繼續看下去前留意前面總合了甚麼。

He is a man of many identities of whom even his wife does not know about.
of whom所指不單是he這個人本身，而是他擁有不同身份這特徵
We have many choices of destination for our vacation this year for where we can enjoy quality times together.
for where所指不是著重描述地點，而是表達縱使地點的選擇眾多但去那地點的意義在後面加以說明
Ocean Park is an amusement park of which it markets itself as an eductional institute.
在前面說的東西本身之處還有一些特別角度的表述
海洋公園本身是一個遊樂場，而這個遊樂場宣傳它是一間教育機構