先行词指物时引导词用that而不用which的情况:
1、先行词有序数词或形容词最高级修饰时,
This is the best composition that has been written in English.
2、先行词是all,something,anything,nothing,everything,little,few,much等不定代词时
There is nothing/little/much that we can do for her.
3、先行词被all,every,no,some,any,little,much等修饰时
I’ve read all the books that you gave me.
4、先行词被the only/very等修饰时
This is the very/last place that they visited yesterday.
5、有两个以上先行词,分别表示人或物时
They talked about the teachers and the schools that they had visited.
6、先行词为基数时
Yesterday I caught two fish,Now you can see the two that are still alive in a basin of water.