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 4 1）不用that的情况 a) 在引导非限定性定语从句时.(错) The tree,that is four hundred years old,is very famous here.b) 介词后不能用.We depend on the land from which we get our food.We depend on the land that/which we get our food from.2) 只能用that作为定语从句的关系代词的情况 a) 在there be 句型中,只用that,不用which.b) 在不定代词,如：anything,nothing,the one,all,much,few,any,little等作先行词时,只用that,不用which.c) 先行词有the only,the very修饰时,只用that.d) 先行词为序数词、数词、形容词最高级时,只用that..e) 先行词既有人,又有物时.举例：All that is needed is a supply of oil.所需的只是供油问题.Finally,the thief handed everything that he had stolen to the police.那贼最终把偷的全部东西交给了警察.
