定语从句在句中作定语，修饰名词或代词，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。 那么怎样判断定语从句?下面我们去了解一下吧!
一、定语从句的识别：
名词(句子)+连接词+句子
其中识别度最高的关键之处，就是连接词，它有三种：
① 关系代词：who, whom, that, which, as, whose
② 关系副词：when, where, why, how
③ 介词+关系代词：介词+whom, 介词+which, 介词+whose
但注意，有时你会看到 in that，但in that=because，算是一种固定搭配，这和定语从句没关系。
这里单独说一下as引导的定语从句吧，因为其它都还比较常见，as相对来说比较生疏。
主要是在same和such之后，定语从句用as引导，但偶尔the same后面也用that.
如：I've never heard such stories as he tells.
我从来没听到过他讲的这种故事。
He is wearing the same suit as(或that) he wore at Mary's wedding.
他穿着与他在玛丽的婚礼上穿的一样的衣服。
二、定语从句的处理
原则：将定语从句完整地切分出来，独立成句。
两个关键点：① 完整地切分;② 独立成句
第一步，切分：切分点在连接词前，如果连接词前有介词那就在介词前。
如：I love this girl / who is beautiful.
I went to Changchun / where I met my wife for the first time.
I have three books / of which the red is my favorite.
第二步，找指代(也就是关系代词的指代对象)：
如：This is the expert / to whom we are turning.
注：turn to = resort to = 求助于……
这句话里的关系代词是 whom , 它的指代对象是the expert.
所以这句话翻译过来是：这就是我们正在求助的那个专家。
第三步，调语序
需要调整语序的也就是关系代词和(介词+关系代词)
还是上面那句话：This is the expert to whom we are turning.
先切分，① this is the expert /
② to whom we are turning
再找到第②句中whom的指代对象，whom=the expert
也就是 to the expert we are turning
这时落实到我们要讲的调语序了，因为我们发现to the expert we are turning,它由于受到定语从句规则的限制，所以不是正常语序，现在我们把它变成正常语序就是：we are turning to the expert
这时，你再翻译成中文时就没有障碍了。
至此，我们总结一下，定语从句的处理就是分三步，1.切分;2.找指代;3.调语序
这样就可以完成了将一个定语从句从英文到中文的转换，所以下次遇到定语从句时，你只管先“咔嚓”来一刀，给它切开，两个句子安安静静地出现在你面前，你就别么费劲地去前置了，那么定语从句就不能前置了吗?也不是不能，语义如果挺顺畅的.你就前置呗，只是能前置的定语从句基本上都退化成后置定语了，比如，an apple which is on the table也可以写成an apple on the table(桌子上的苹果)
a way which is to solve the problem也可以写成 a way to solve the problem(解决这个问题的方法)
定语从句的几个难点
难点一：定语从句与并列句的区别
观察下面三个句子：
Hong failed in the College Entrance Examination, ________ disappointed his mother.
Hong failed in the College Entrance Examination and ________ disappointed his mother.
Hong failed in the College Entrance Examination; ________ disappointed his mother.
(提示：判断是定语从句还是并列句，要注意句中的标点符号和句中的连接词。)
例1：Tom’s mother kept telling him that he should work harder, but _____ didn’t help.
h
例2：The weather turned out to be very good, _____ was more than we expected.
h
e
例3：The mother told her lazy son to work instead of staying at home; ____ didn’t help.
h
难点二：介词+关系代词引导定语从句中介词的选择
“介词+关系代词”可引导限制性定语从句也可引导非限制性定语从句，可从以下几点定位关系代词前的介词。
1.介词与先行词搭配是一种固定搭配
I still remember the day ____________ I first came to school.
The company ______________ I once worked has changed much.
2.介词与从句中动词的搭配
He is a man of great knowledge, _____________ much can be learned.
In the dark street, there wasn’t a single person _____________ she could turn for help.
3.介词与从句中形容词的搭配
China is a beautiful country, _____________we are greatly proud.
The teacher talked about some subjects _________________ the students were interested.
4.与名词之间的搭配
He may be late, ________________ we ought to wait for him.(如果是这样)
Call me at six o’clock, __________________ I should get up.(到那个时候)
Ex:
(1)There is a room, _______________________ faces the river.
那儿有一间房子，窗户面对这条河。
(2)They are the very people _______________________ for help.
他们就是那些你可以向其求助的人。
(3)China has many islands, _______________________ Taiwan is the largest.
中国有很多岛屿，台湾是其中最大的一个。
(4)They arrived at a house, _______________________.
他们到达一所房子，前面坐着一个小男孩。
(5)Gun control is a subject ________ Americans have argued for a long time.
which which
t which which
(6)By nine o’clock, all the Olympic torch bearers had reached the top of Mount Qomolangma, ________ appeared a rare rainbow soon.
which which
which e which
(7)For many cities in the world, there is no room to spread out further, _____ New York is an example.
which which
which which
注意：The way ________ he explained to us was quite simple.
The way ________ he explained the sentence was simple.
难点三：引导词as , which
1.引导非限制性定语从句，指代整个主句内容时的区别：
(1)表达“正如”之意时，用as, 如果仅指代整个主句内容而没有“正如”之意，则用which。
He went abroad, ______ was unexpected.
She is a good mother, _____ her mother used to be.
(2)当从句位于主句前面时，用as。
______ is known to everybody, the moon travels round the earth.
2.限制性定语从句中有such, the same 时，其后常用as 引导定语从句。
He is such a good teacher _______ we all love and respect.
This is the same pen _______ I lost.
h既可指代整个主句内容，又可以指代先行词。
The river, _______ flows through London, is called the Thames.
常与从句中的know, see, hear, expect等动词连用，也常用于as often happens, as is often the case等句子中。
He was absent from school, _______ is often the case.
难点四关系代词与关系副词(补全法或还原法)
you still remember the chicken farm ________ we visited three months ago?
an hour, we can travel to places ________ would have taken our ancestors days to reach.
pre-school children go to a day care centre, ________ they learn simple games and songs.
练习：
16:30, ________ was almost closing time, nearly all the paintings had been sold.
h
2.A woman with a bleeding hand hurried in and asked, “Is there a hospital around ________ I can get some medicine for my wounded hand?”
h
e
3.—How do you like the film Examination 1997, Mr. Li?
—It brings the hours back to me _____ I was forced to raise pigs in a faraway village.
e
难点五先行词为point, case, situation等时所构成的定语从句
1.—Do you have anything to say for yourself?
—Yes, there’s one point ______ we must insist on.
e
D./
2.I have reached a point in my life ______ I am supposed to make decisions of my own.
h e
new partnership with France Telecom is really a win-win situation _____ both sides benefit a great deal.
h
e
y, we’ll discuss a number of cases _____ beginners of learning English fail to use the language properly.
h
e
’s helpful to put children in a situation ___________________________________.
把孩子们放在一个能使他们从另外一个角度认识自己的环境中对他们有益。
there is just one point _____________________________________.
现在只有一点你能弄清楚。
