介词加which的用法 还有in which 可以等于where，但能等于when吗，有人说有时也

介词＋which ／whom的用法 1．语法作用：“介词＋关系代词”在从句中主要起关系副词的作用，即在定语从句中充当状语：
（1）表示地点，时间和原因的“介词＋which”分别相当于 where，when，why。
I have found the book in which the names of all the early satellites are mentioned．（SEFC 2A L．55）（＝I have found the book．The names of all the early satellites are mentioned in it．）
The earth on which ／where we live is a planet．
I'll never forget the day on which ／when I joined the League．
I know a wood in which ／where you can find roses．
Is there any reason for which ／why you should have a holiday？
（2）way后常用that代替in which，也可省略that。
I really don't like the way that he talks．
That was the way in which the old lady looked after us．
Do it the way I showed you． 2．“of ＋which”起形容词的作用，相当于whose（用来指物），其词序通常是“n．＋of which”。
They live in a house whose door ／the door of which opens to the south．
He's written a book whose name ／the name of which I've com- pletely forgotten．
更多详细内容可以参照文库：http://wenku.baidu.com/link?url=ED_veH55Ijkt6JwxNk4YsoJertUh2fK6ChTgTriNqTv-XHhBvJ800G9-Qj8XgPWgHy21vqr9BDrUwJ8_gpDFtZfzG5ZgsLCg8CXzuR-GAZe

是的，有时in which 也等于w'hen

介系词加关系代词，可以引导定语从句，这里的关系代词指人时用whom，指物时用which，指地点时还可以用关系副词where。
这里的介系词的选用，或根据上下文要表达的具体意思，或者根据先行词的习惯搭配，或根据定语从句中某些字或短语的固定搭配，有时候，这个介系词可能就是作定语从句谓语的短语动词的一个固定介系词。
介系词加关系代词结构，可以在从句中作状语或定语，并可以修饰别的名词一同作状语。如：
This is the ring on which she spent a thousand dollars.
The economist with whom all of us are familiar will visit our company.
I can't remember the age at which he won the prize.
Excitement deprived me of power of utterance, in which case I would stand there nodding and waving.
Water boils at two hundred and twelve degrees Fahrenheit, at which temperature it changes to gas.
A telegram half of which was false deceived them.
It was a very agreeable place located within two small hills, in the midst of which flowed a great river.
She stood near the north window, from where she could see the whole garden.
两个字或三个字构成的短语动词，在定语从句中一般不能把介系词分开放在关系代词前面，如：
The music which I was listening to was very good.
This is the girl whom he will take care of.