1. which 用法
which 在英文文法內屬於關係代名詞(relative pronoun)， 指稱「一件事/物件」，例子有﹕
I don’t know which pen is yours (我不知道那支筆才是你的)
Apple was founded by Steve Jobs (Apple由Steve Jobs 創辦)
Apple has changed the world. (Apple改變了這個世界)
Apple, which was founded by Steve Jobs, has changed the world. (由steve jobs 創辦的Apple改變了這個世界)
要記得，which 一定是跟在noun後面!知道了which的基本用法和意思之後，我們就可以看看which 前面加上不同介詞到底是意思啦! 首先是in which﹕
2. in which 用法及中文意思
1. in whcih 可以理解為將句子後面的介詞(preposition，就是in/ of/ on 等)搬到前面，從而令句子變得更加正式，例子有﹕
I grew up in this neighborhood.
This neighborhood has been rebuilt.
This is the neighborhood in which I grew up has been rebuilt.= This is the neighborhood which I grew up in has been rebuilt (我從小住的那個社區現在已被重建啦)
與此同時，當which是用來形容事物時，in which 就是用來形容「地點」，將兩句句子連在一起， 同時亦可以用where代替，但in which 就有比較強調「在..裡面」的意思，例如﹕
I once studied in this university
this university is the best one in HK.
This is the university where I once studied is the best one in HK= This is the university in which I once studied is the best one in HK (強調他曾經在這家大學裡面讀過)
3. of which 用法
of which的用法和原理跟in which相似，首先同樣是介詞前置的用法﹕
Jane is now working in a company.
You must have heard of this company.
Jane is now working in a company which you must have heard of. = Jane is now working in a company of which you must have heard. (Jane現在的公司你一定都聽過)
2. of which 的另外一個意思是「其中」。
當of which是用作連接兩句句子的時候，of which 後面的那句就是在形容前句的其中一項物件，例如﹕
前句﹕There are 3 pens on the desk
後句﹕The pen in red is mine
There are 3 pens on the desk, of which the pen in red is mine.（桌上有3枝筆，其中紅色那枝是我的筆）
在這個例子裡面，of which 後面的 ’the pen in red’ 就是在說桌上3枝筆的其中一枝
4. by which 用法
He was known by a nickname at school.
His nickname is ‘Spiderman’
The name by which he was known at school is Spiderman.（他以「蜘蛛人」的綽號在學校內非常有名）
2. by which 的另外一個意思是「藉由…」，
前句﹕He learns English in many ways.
後句﹕He takes online English courses to practice his oral English.
One of the ways by which he learns English is taking online English courses to practice his oral English. （他其中一個學英文的方法是藉由線上英語課程練習英語會話）
- The book is sold out + The book is written by JinYoun = ?
- I keep all my books in the box + The box was bought from LogOn = ?
- Harry Potter has been translated into over 80 languages + The English version of Harry Potter is the most popular and original one = ?
- There are 365 days in a year + My favourite day of the year is my birthday = ?
- 這句有錯嗎? Hong Kong is a crowded city where more than 7 millions people live in
5. at which, on which, for which 用法及意思
和in which/ of which一樣，基本上所有「介詞+which」的第一個用法都是介詞前置，也就是將後句最後的介詞放在which 前面。
at which = 「在…某一點上」
The picture at which everybody is starring was painted by Da Vinci. (那幅人人都在望的畫是達文西的作品)
for which = 「為了….」
I will buy you the reference book for which you asked (我會買你提過的那本參考書給你)
on which =「在..上面」
You can take my key from my desk on which there are many photos.(你可以在我的桌上拿我的鑰匙，我的桌上有很多照片)
6. who/ whom用法
和which類似嘅的relative pronoun還有who/whom, 不過形容的是人而不是事物。當你指的人是句子的subject時用who指稱，如果是object就用whom指稱，例如﹕
He is a teacher
He teaches English online
He is a teacher who teaches English online.
He loves the teacher very much
The teacher teaches English on AmazingTalker
He loves the teacher whom teaches English on AmazingTalker
1. The book which is sold out is written by JinYoun
2. The box in which I keep all my book was bought from LogOn.
3. Harry Potter has been translated into over 80 languages, of which the english version is the most popular and original one.
4. There are 365 days in a year, of which my favourite is my birthday.
5. 最後多了一個’in’, 用where的話要拿走preposition，你亦可以寫Hong Kong is a crowded city in which more than 7 millions people live