限制性定语从句讲解
定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词，词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出，定语从句分为限制性定语从句与非限制性定语从句。
关系代词有:who, whom, whose, that, which等。关系副词有: when, where, why等。
一、关系代词引导的定语从句
关系代词和关系副词放在先行词和定语从句之间，起连接作用，同时又可做定语从句的一个成分。当关系代词做宾语时能够省略。
定语从句中的谓语动词必须在人称上和数量上和先行词保持一致。
（1）who, whom, whose,that代替的先行词是人的名词或代词，他们在从句中作主语，宾语，定语等:
Is he the man who/that wants to see you?他就是你想见的人吗？（who/that在从句中作主语）
He is the man whom/ that I saw yesterday.他就是我昨天见到的那个人。（who/that作从句的宾语）
The girl whose father is a doctor likes dancing（whose在从句中作定语）
* Whose也可用来指人也可用来指物，(都只用作定语, 指物时它能够同of which互换）, 例如:
They hurried to help the man whose car had broken down. 那人车坏了，他们赶紧去帮他。
Please pass me the book whose (of which) cover is green. 请递给我那本绿封面的书。
（2）which, that 它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，例如:
The cat which/that run away from the room was mine.
那只从房间逃走的猫是我的。（which/that在从句中作主语）
限制性从句
The bus which/that you saw has already left.
你看见的那辆公交车已经离开了。(which / that在句中作宾语）
关系副词可代替的先行词是时间、地点，理由的名词，它们在从句中作状语。
when, where, why（相当于"介词+ which"结构，所以常常和"介词+ which"结构交替使用，例如:
I can remember the day when (on which)we met. 我还能记得我们见面的那天。
Beijing is the place where (in which) I was born. 北京是我的出生地。
This is the reason why (for which) he was late for school? 这就是他上学迟到的理由。
三、当先行词是时间，地点，原因等词时，关系代词与关系副词的判断
方法一: 用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词which/that；而不及物动词则要求用关系副词when/where/why等。
方法二：判断先行词在定语从句中的成分，如果它们在从句中作主语或宾语，则用which/that，否则就是作状语，选用when/where/why等。例如:
This is the mountain village where I stayed last year.
This is the mountain village which/that I visited last year.
I'll never forget the days when I worked together with you.
I'll forget the days which/that I spent in the countryside.
注意事项：
1．从句谓语是“动词+介词”结构时，有些介词可以提到关系代词前，这时关系代词只能使用whom(指人)，which(指物)，介词未提前时，按原规则使用关系词。
This is the man who/that we talked about just now. 这就是我们刚才谈论的那个人。
This is the man about whom we talked just now. 这就是我们刚才谈论的那个人。
2.关系代词that,who,whom,which等在从句中作宾语时，可以省略。但当它们前面有介词时不能省。
This is the tiger Wusong killed . 这就是武松杀死的老虎。
This is a computer his father bought. 这就是他父亲买的电脑。
特殊情况：
（1）.不用that的情况
a.在引导非限定性定语从句时。
The tree, which(不能用that) is four hundred years old, is very famous here.
b.介词后不能用。
We depend on the land from which（有能用that）we get our food.
c.先行词为those, people 时
Those who(不能用that) are lazy cant pass the exam.
d.当句中已有that时
That is the tree which (不能用that) I planted many years ago.
e.先行词为all, anyone, ones, one 指人时
One who (不能用that)doesn't work hard will never succeed in his work.
(2). 只能用that作为定语从句的关系代词的情况
a.在不定代词，如：anything, nothing, everything等作先行词时，只用that，不用which。
All that is needed is plenty of money.
Finally, the thief stole everything that was in the office.
b.先行词有the only, the very, the same, the last ,all, much, few, any, little等修饰时，只用that。
He is the very man that helped the girl out of the water.
c.先行词为序数词、数词、形容词最高级时，只用that。
The first English book that I read was "The Prince and the Pauper".
d.先行词既有人，又有物时。
He talked about the teachers and schools that he visited.
e.当主句是以who 或which 开始的特殊疑问句时，用that 以避免重复。
Who is the person that is standing at the bus stop.
f.关系代词在从句中做表语
He is not the man that he used to be.
j.以here is开头的句子
Here is the book that the teacher gave.
h.在there be句型中，句子的主语是先行词，而且又是物
There is a book on the desk that belongs to Tom.
(3).如果先行词是way(方式)，关系词从句中作状语时相当于“用…方式”（in this way），通常不用关
系词，偶尔用that，在较正式的文体里才用in which来引导。如作主语、宾语、表语时则用that/which..
The way he did the work was different from the way in which we were used to doing it.
This is the way that/which he can think out.
附：限制性和非限制性定语从句简介
定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：
This is the house which we bought last month.这是我们上个月买的那幢房子。（限）
The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的（非限)