4. 只用 which ,不用that 的情况：

　　1).关系代词前有介词时。

　　This is the cage that / which Polly lives in.

　　= This is the cage in which(where) Polly lives .

　　2).先行词本身为 that.

　　The clock is that which tells the time.

　　3). 在非限制性定语从句中。

　　His English, which used to be poor , is excellent now.

　　定语从句专项练习

　　1.Sorry, we don’t have the coat ________ you need.

　　A. what B. who C. whom D. which

　　2.This is the dictionary ________ Mum gave me for my birthday.

　　A. which B. what C. whose D. whom

　　3.Do you know the man ________ is sitting behind Nancy?

　　A. what B. which C. who D. whom

　　4.The book ________ he bought yesterday is very interesting.

　　A. / B. why C. when D. what

　　5.I have found some pictures of the most interesting places ________ you can visit during the winter holidays.

　　A. where B. which C. what D. that

　　6.I’d like to tell you about the table manners ________ you should know when you visit Korea.

　　A. which B. who C. what D. how

　　7.I shall never forget those years ________ I lived on the farm with the farmers, ________has a great effect on my life.

　　A. when; who B. that; which

　　C. which; that D. when; which

　　8.Is oxygen the only gas ________ helps fire burn?

　　A. that B. / C. which D. it

　　9.Is ________ some German friends visited last week?

　　A. this school B. this the school

　　C. this school one D. this school where

　　10.---What kind of music do you like?

　　---I like music ________ has great lyrics.

　　A. that B. what C. who D. whose

　　11.That is the only thing ________ I bought from the supermarket.

　　A. which B. that C. what D. where

　　12.The place ________ interested me most was the Children’s Palace.