定語從句中,有時where、when等可以與介詞+which結(jié)構(gòu)相互替換：
介詞的使用是根據(jù)先行詞而言的.
例如：I'll go to the park where I can fly a kite.我將去公園,在那里我可以放風(fēng)箏.此處where=in which,因?yàn)閕n the park.
I‘ll go to the station where I'll pick up my brother.我將去車站,在那里我將接我的弟弟.此處where=at which,因?yàn)閍t the station.
至于when的情況,也是看先行詞：
例句：It was five o’clock at which I was doing my work.那時候是五點(diǎn),我正在工作.
It was Sunday on which I had a picnic.那是一個周日,我們?nèi)ヒ安土?
of which是指與先行詞是從屬關(guān)系.
例句：I have some friends ,of which Tom is the best one.
并不是所以情況下都可以和介詞+which結(jié)構(gòu)相替換,得看where,when等疑問詞是否能在不引起歧義的情況下表達(dá)出相應(yīng)的含義.