定语从句用that的情况

1.that即可代表事物也可代表人,which代表事物；它们在从句中作主语或宾语,that在从句中作宾语时常可省略关系词,which在从句中作宾语则不能省略.而且,如果which在从句中作“不及物动词＋介词”的介词的宾语,注意介词不要丢掉,而且介词总是放在关系代词which的前边,但有的则放在它原来的位置
2.which作宾语时,根据先行词与定语从句之间的语义关系,先行词与which之间的介词不能丢
3.代表物时多用which,但在带有下列词的句子中用that而不用which,这些词包括all,anything,much等,这时的that常被省略
当先行词是anything,everything,nothing (something 除外),few,all,none,little,some 等代词时,或者是由every,any,all,some,no,little,few,much 等修饰时
(1) Have you taken down everything that Mr.Li has said?
(2) There seems to be nothing that seems impossible for him in the world.
(3) All that can be done has been done.
( 4) There is little that I can do for you.
This is the very novel (that) I want to buy .此句的先行词是物.
Mr Smith is the only foreigner ( that) he knows .此句的先行词是人.