习惯上要用that引导的定语从句

(1)当先行词是指物的all, little, few, much, any, anything, everything, nothing, none, the one时，或先行词被all, little, few, much, any, every, no等修饰时。

All that can be done has been done. 能做的都已经做了。

He will tell you everything that he heard about it.他将告诉你他所听到的关于这件事的一切。

There is little work that is fit for you. 没什么工作适合你做。

I have eaten all the food that is left. 我把剩下的所有食物都吃了。

(2)先行词是序数词或最高级形容词时，或者先行词被序数词(包括last, next)、最高级形容词及the only, the very 等修饰时。

This is the first film that I have seen since I came here.这是我到这里后所看的第一场电影。

This is the best that has been used against pollution. 这是用来防止污染的最好办法。

This is the very book that I am looking for. 这正是我一直在寻找的那本书。

(3)先行词包括人和物时。

They often talk about the people and the things that they are interested in. 他们常常谈论那些他们感兴趣的人和事。

(4)当主句是以who或which开头的疑问句时，为了避免重复，多用that引导。如：

Which is the house that caught fire last night? 昨晚失火的是那座房子？

Who is the lady that is playing the piano? 在弹钢琴的那位小姐是谁？

习惯上不用that引导的定语从句

(1)在非限制性定语从句中，不以能用that引导。

Yesterday I met Mary, who seemed very excided. 昨天我碰到了玛丽，她显得非常兴奋。

(2)直接在介词后作宾语时，不能用that引导，要用whom, whose或which，且不能省略。

The house in which we live is not large. 我们住院的房子不大。

I know the young man with whom you live. 我认识和你住在一起的那个年青人。

但当介词放在从句的末尾时，可以用that替代which, who替代whom，也可以省略关系代词。如：

The house (which/that) we live in is not large. 我们住院的房子不大。

I know the man (whom/who/that) you live with. 我认识和你住在一起的那个人。

(3)当先行词是指人的all, any, few, one(s), anyone, everyone, people 等时，多用 who。如：

None so blind as those who won't see. 睁眼不看事实的人眼最瞎。

Anyone who is over sixteen is allowed in. 任何超过十六岁的人都允许进去。

I met someone who said he knew you. 我碰到一个人，他说认识你。

He who has a mind to beat his dog will easily find his stick. (谚)欲加之罪,何患无辞。

(4)当先行词与关系代词之间有较复杂的短语或从句隔开时。

I was the only person in my office who was invited. 我是我们办公室里唯一受到邀请的人。

A new master will come tomorrow who will teach you German. 有位新校长明天来，他将教你们德语。