anything， everything， nothing， any， little， one， few， much， all， none等时。如：
a.There isn't much that I can do. b.He is one of the few that can work it out in five minutes.
a.The book is the best that I have read. b.This is the biggest laboratory that we have ever built in our university.
a.It is the third one that I've bought. b.This is the first place that I‘ve ever visited.
四、当先行词被the very， the only等词修饰时。如：
a.Is this the very museum that you visited the other day？ b.This is the only book that I need at present.
They talked of things and persons that they remembered in the school.
She is wearing the same dress that she wore yesterday.
a.This is no longer the place that it used to be. b.He is not the man that he was.
a.Which is the book that he bought yesterday？ b.Who that you have ever seen can beat him in the game？