定语从句何时必用that

但在下列情况中,只能用 that,不用 which：
①当先行词是 all,a lot,(a) little,few,much,none,anything,something,everything,nothing 等词时.如：
All that can be done has been done.
In this factory I saw little / much that was different from ours.
②当先行词被 all,any,no,much,little,few,every 等限定词所修饰时.如：
We heard clearly every word that he said.
③当先行词是序数词或被序数词所修饰时.如：
The first thing that should be done is to get the tickets.
When people talk about Hangzhou,the first that comes to mind is the West Lake.
④当先行词是形容词*或被形容词*所修饰,以及先行词被序数词和形容词*同时修饰时,如：
Is that the best that you can do?
That’s the most expensive hotel that we’ve ever stayed in.
This novel is the second best one that I have ever read.⑤当先行词被 the very,the only,the next,the last等所修饰时.如：
This is the very book that I want to find.
⑥当先行词为指人和指物的两个并列名词词组时.如：
The guests spoke highly of the children and their performances that they saw at the Children’s Palace.
She described in her compositions the people and places that impressed her most.
⑦当主句是以 which 开头的特殊疑问句时.如：Which is the car that killed the boy?