關(guān)系代詞直接放在介詞后面時,要用which,不用that.例：
Read the passage to which I referred in my talk.
讀一下我在演講中提到過的那段文章.
His new car,for which he paid ￡7000,has already had to be repaired.
他花700英鎊買來的那輛新車已經(jīng)不得不修理了.
which還可以用作關(guān)系限定詞,后跟名詞,that則不能這樣用.例：
He changed his mind for the second time,after which I refused ever to go out with him again.
他第二次變卦,以后我再也不跟他出去了.
The postman comes at 6.30 in the morning,at which time I am usually fast asleep.
郵遞員早晨六點半就到,而這時我通常還熟睡著呢.
He may come,in which case I'll ask him.
他也許會來,來了我就問他.
There are 2 left,one of which is almost finished and the other of which is not quite.
剩下兩件事,一件快做完了,另一件還有得做.
引導(dǎo)非限制性定詞從句時,一般要用which,不用that.例：
Football,which is a popular game,is played all over the wofld.
全世界都踢足球,它是一項很受歡迎的運動.
She spent all evening talking about her latest book,which none of us had ever heard of.
她花了整個晚上談她最近的新書,關(guān)于這本書,我們沒有一個人聽說過.