1.的確,in which可以等于when,也可以等于where,但不會等于why.
關(guān)鍵是看定語從句中缺少時間狀語還是地點狀語.
2.例如：
1）I'll never forget these days in/during which I stayed with you.
= I'll never forget these days when I stayed with you.
我永遠(yuǎn)不會忘記我和你待在一起的日子.
其中：in/during which I stayed with you = when I stayed with you
= I stayed with you in/during which = I stayed with you in/during these days
2）This is the city in which I stayed last year.
= This is the city where I stayed last year.
這就是那個去年我待的地方.
其中：where I stayed last year = in which I stayed last year
= I stayed in which last year = I stayed in the city last year.
3.另外,有的in which找不到合適的關(guān)系副詞代替.
如：I dislike the way in which you treat me.
我不喜歡你對待我的方式.
其中：in which you treat me = you treat me in which
= you treat me in the way
4.for which = why
如：Can you tell me the reason why you were late?
= Can you tell me the reason for which you were late?
你能告訴我你遲到的原因嗎?
其中：why you were late = for which you were late
= you were late for which = you were late for the reason