介词加which引导的是定语从句，常见的用法有：in?which可以翻译成“在……里面”，for?which可以翻译成“为了……目的”，on?which可以翻译成“在……的上面或具体时间的某一天”，at?which可以翻译成“在……里面或在……上面”。

1.in?which 在……里面

The?school?(that/which)?he?once?studied?in?is?very?famous.??

=?The?school?in?which?he?once?studied?is?very?famous.?

2.for?which 为了……目的

Tomorrow?I?will?bring?here?a?magazine?(that/which)?you?asked?for.???=?Tomorrow?I?will?bring?here?a?magazine?for?which?you?asked.?

3.on?which 在……的上面或具体时间的某一天

I?have?a?dresser?in?my?bedroom,?which?there?are?many?cosmetics?on.??

=?I?have?a?dresser?in?my?bedroom?on?which?there?are?many?cosmetics.

4.at?which 在……里面或在……上面

The?dumpling?House?which?he?often?has?dumplings?at?is?very?popular.?

=?The?dumpling?House?is?very?popular,?at?which?he?often?has?dumplings.