定语，指在句子里专门用来修饰名词的部分，它可以是个单词或短语，也可以是个句子。
一个句子在另一个句子里面作定语，或把整个定语从句，看成一个很大很大的形容词。
所谓定语从句，就是两个并列句的合并。
Captain Fawcett’s first passenger was a doctor and the doctor flew from Birmingham to a lonely village in the Welsh mountains.
改为定语从句：Captain Fawcett’s first passenger was a doctor who flew from Birmingham to a lonely village in the Welsh mountains.
定语从句的连接词叫关系词，分为两大类：
代词类关系词：1、关系代词；2、关系代词所有格；3、复合关系代词。
副词类关系词：关系副词。
一、关系代词，其作用是代替前面的先行词，在定语从句中作主语、宾语、表语。
代替人时，主格用who，宾格用whom。代替物或整个句子，无论主宾，均用which。
先行词为一般名词，关系代词引导的定语从句，称为限定性定语从句。
He is a man whom we should respect.
注意：在美语中，whom作宾语时也可用who代替。
In a few years the small workshop had became a large factory which employed 728 people.
In 1948, he went to lake Kivu to observe a new volcano which he later named Kituro
Forest fires are often caused by cigarette ends which people carelessly throw away.
作介词的宾语时，可以将介词移动到关系词之前。一般正式的书面语时把介词放在关系代词前面。
Peter is a man whom I enjoy working with. =Peter is a man with whom I enjoy working.
注意：美语中不要以介词结尾，那是没文化的表现。
The city in which I live is very large. =The city which I live in is very large.
若定语从句只对先行词进行补充说明，则关系代词前可加上逗号，称为非限定性定语从句。
先行词为一般名词，但其前面已经有限定词或形容词修饰时，其既可用于限定性定语从句，也可用于非限定性定语从句。
He waved desperately to his companion, who had been water-skiing for the last fifteen minutes.
先行词为专有名词（人名和地名）及独一性名词（如：father，mother）时，因为本身就有特殊性，其后关系代词引导定语从句，必须是非限定性定语从句。
Einstein, who was a great scientist, created the theory of relativity.
Beijing, which is the capital of China, has developed into an international city.
Among them will be Debbie’s mother, who swam the channel herself when she was a girl.
先行词为整个主句时，定语从句也多是非限定性定语从句。
Jimmy is a naughty boy, which everyone knows.
That也可以作为关系代词，取代who，whom，which，但是that前不能有逗号，也不能有介词。
This is the sort of things that Jeremy loves.
A game that/which is very popular with these young swimmers is the underwater tricycle race.
注意：下列情况只能用that：
1、 先行词同时出现人和物时。The scientist and his inventions that the article deals with are quite familiar to us.
2、 先行词是不定代词something，anything，nothing，everything时。
I would much rather receive something that made me laugh.
A variable is something that can be changed and controlled.
3、 先行词被绝对性形容词修饰时，如序数词，形容词最高级，the very，the only，all，every，no等修饰时。
All the students that are studying in our class is hardworking.
Of course, the Hubble is above the earth’s atmosphere, so it will soon be sending us the clearest pictures that we have ever seen.
4、 句中有两个相同关系代词引导的定语从句时，为避免重复，其中一个用that。
He works hard, which is a fact that is known to us.
My best friend was devastated by the letter which she received that rejected her application to university.
There was no trace of fingerprints, but the inspector found a dirty red bundle that contained jewellery which the old lady said was not hers.
限定性定语从句中，若关系代词作及物动词的宾语，该关系代词可省略，若作介词的宾语，则将介词放在句尾，再省略关系代词。
It is one of the ugliest faces (that) I have ever seen.
That was all (that) she remembered.
The pictures (that/which) it sent us were very disappointing because its main mirror was faulty.
Peter is a man (whom) I enjoy working with.没有whom，with不能提前。
造句练习二十三：
1、 双语人士（bilingual）就是能说两种语言一样好的人。A bilingual is a person who can speak two languages equally well.
2、 不要和自己了解不充分的人交朋友。Don’t make friends with those who you don’t know well.
3、 要参加比赛的人必须在本周五之前报名（sign）。The people who want to attend the competition must sign before by this Friday.
4、 露露买了那件她想要的价值不菲的裙子。Lulu bought that expensive dress which she wanted.
5、 我把我银行账户里面的最后一美元花掉了。I spent the last dollar that I had left in my bank account.
6、 我喜欢我的学校，它以优良的设施闻名。I like my school, which is famous for its excellent facilities.
7、 我在聚会上遇到很多小学同学，其中一些我都认不出来了。I met many elementary classmates at the party, some of whom I don’t recognize.
8、 彼得是个非常优秀的工程师，这点我们都知道。Peter is a very excellent engineer, which we all know.
9、 这位是我的女朋友，她英语说得非常流利。This is my girlfriend who can speak fluent English.
二、关系代词所有格。由代词所有格his，her，their，my，your，its变化而来，关系代词所有格和后面的名词共同作定语从句的主语、宾语。无论代替人还是代替物，关系代词所有格均可用whose，修饰物也可用of which，of前面是代词的时候，不用whose，用of whom。
Many people whose homes are in town want to live in the country.
Be a man whose word is as good as your bond.做一个说话可靠的人。
Success is journey whose initial step is paved with an inner stirring.
从句可改为;
Success is a journey of which the initial step is paved with an inner stirring.
Success is a journey, the initial step of which is paved with an inner stirring.
名词/代词 of whom/which，这种结构，属于非限定性定语从句，表示从属关系。
Light is the fastest thing in the world, the speed of which(whose speed) is 300,000 kilometers per second.
The old man has three sons, one of whom is a doctor.不能改为whose one，因为先行词是one。
There are 300 college students in the small hall, most of whom are freshman. 不能改为whose most。
造句练习二十四：
1、 这是玛丽，他爸爸是我们学校的校长。This is Mary, whose father is the headmaster of our school.
2、 我们住在一栋老房子里，它的屋顶可能随时会崩塌。We live in an old house, whose roof may collapse anytime.
3、 这就是那台硬盘中毒的电脑。This is the computer whose hard disk is infected with a virus.
三、复合关系代词what，是先行词和关系代词融为一体，形成的关系代词，相当于the thing that，所以复合关系代词引导的定语从句，前面绝对没有先行词。
What John said may be true. =The thing that John said may be true.
也可以用被动语态：what was said by John may be true.
He was astonished at what he found.
What也可由all that取代。Now all that was needed were the parents, but they were absent.
All that Billy told us a year ago has become true.
造句练习二十五：
1、 我没有听到你刚才说的，能再说一遍吗？I didn’t hear what you just said, could you say that again?
2、 我知道你的意思，但是我不同意。I know what your mean, but I can’t agree with you.
其他不常用符合关系代词：代替人whoever=anybody who，whomever=anybody whom凡是……的人。
Whoever plays with fire gets burnt. =Anybody who plays with fire gets burnt.玩火自焚
I’ll teach English to whoever wants to learn it. =I’ll teach English to anybody who wants to learn it.
二、副词类关系词，共三种，均由介词 关系代词which变化而来
1、 where=in which，on which，at which代替表地方的名词
2、 when=in which，on which，at which代替表时间的名词
3、 why=for which代替the reason
在限定性定语从句中，where不能省略，when和why可以省略。
Mrs. Brabant is talking to the manager of the local factory where the crop is processed.
这句话里面where=in the factory=in which在从句里面作地点状语。
There will be moments in life when you are confronted with new options.人生中总有会面对新选择的时候。When=in these moment=in which作时间状语。
Unsuccessful people can always find reasons why they are not doing well. Why=for these reasons=for which。不仅可以省略why，还可以保留why，省略reasons。
Unsuccessful people can always find why they are not doing well.这样就变成宾语从句了。
The way后面的定语从句，先行词是名词the way的时候，后面的关系副词是in which或that，而且可以省略。
The assistant who served her did not like the way (in which/that) she was dressed.接待她的售货员不喜欢她的那副打扮。
I hate the way in which he stares at me.
I liked the way (in which/that) she organized the meeting.
The only way that they can preserve their history is to recount it as sagas.他们保存历史的唯一办法是将历史当作传说讲述。
注意：上面句型中的the way（in which/that）可被how取代，变成宾语从句，意思不变。但用的不多，仅需了解。
The assistant who served her did not like how she was dressed.
I liked how she organized the meeting.
I hate how he stares at me.
The way也可作副词联系引导方式状语从句，详见本章第三节方式状语从句部分。
I admire the way you speak to your students. (定从)
You should do it the way you were taught. (方式状语从句)
Where，when代替的先行词作Be动词的表语时，可省略先行词，保留关系副词。
There is (the place) where he was born.
That is (the day) when he will come.
某些表示时间的名词短语，后面接着没有引导词的句子，其实就是省略了关系副词when。
By the time, at the time, next time, every time, the first time, the day……。
Every time he wanted to come into the garden he would bark until someone opened the gate.
By the time you read this, the Hubble’s eagle eye will have sent us thousands and thousands of wonderful pictures.
造句练习二十六：
1、 上午十一点是考试结束时间，那时所有学生都必须放下笔（put down）。Eleven a.m. is the time when the exam will be over and all students must put their pens down.
2、 我想知道你今天上午上学迟到的原因。I want to know the reason why you late to school this morning.
3、 月球上有一个地方，是Neil Armstrong所踏出的第一步。There is a spot on the moon where Neil Armstrong take his first step.
4、 这是他处理问题的方法。This is the way that he handled problems. = This is how he handled problems.
5、 我们有时把荒岛想象成某种阳光普照的天堂。We sometimes imagine a desert island to be a sort of paradise where the sun always shines.
