1、 当先行词是all, little, few, much, something, everything, anything, nothing, none等不定代词时。如: Everything that happened then was like a nightmare.当时发生的一切就像是一场噩梦。
I will tell him all that you told me at the ball.我要把你在舞会上跟我说的话全都告诉他。
2、 当先行词被only, any, few, little, no, all, just, very(恰好的,表示强调)等词修饰时。例如: The only thing that we could do was to wait.我们能做的只是等待。
That’s the very thing that we can do.那正是我们能做的事。
3、当先行词是序数词、形容词最高级或先行词被序数词或形容词最高级修饰时。例如:
The first place that we visited was the Great Wall.我们参观的第一个地方是长城。
This is the best novel that I have ever read.这是我看过的最好的小说。
4、被修饰词为数词时。例如:
Yesterday I caught two fish and put them in a basin of water. Now you can see the two that are still alive. 昨天我捉到了两条鱼,把它们放在一盆水里。 你可以看到那两条鱼还活着呢。
5、主句是There be结构,修饰其主语的定语从句宜用that作关系代词修饰物。例句:
There’s still a room that is free.还有一个空房间。
6、先行词中同时包括人和物时。例如:
We talked about the people and the villages that we remembered.我们谈论了我们记得的人和村子。
He asked about the factories and workers that he had visited.他问起他去过的这几家工厂和工人的情况。
7、当主句中有who, which时,而定语从句中也要用到who或which时,为了避免who…who, which…which等重叠,定语从句要用that引导。例如:
Who is the man that is standing by the door? 站在门边的那个男人是谁?
Which of the two cows that you keep produces more milk? 你养的那两头奶牛中哪一个产奶多?
8、人或物在定语从句中表语时,用that引导定语从句,而that通常也可以省略。例如:
He is no longer the man that he was.他不再是过去的他。