1、需要注意的问题
保持谓语和先行词的一致
e.g. He is one of the greatest writers who are living now.
e.g. He is the only one of the boys who has joined the army.
whose引导定语从句时，人、物皆可。
不能只看先行词，还要注意引导词在句子中充当什么成分。
避免关系词的重复，被关系代词说替代的部分不可在从句中重复出现。
e.g. This is the book we have read it together.
reason, way后关系词的用法
e.g. This is the reason (for which/ why/ that) he was absent yesterday.
e.g. I don’t like the way (in which/ that) he does everything.
在比较级中，than充当关系代词，在从句中作主语。
e.g. The results of his study have turned out to be more satisfactory than was expected.
2、使用that的几种情况
先行词前有形容词最高级或序数词修饰
先行词前有不定代词修饰，如the same, the only one, all, both, everything, nothing
当主句是以who, which开始的特殊疑问句时，从句用that，避免重复
先行词既指人，又指物
e.g. We know nothing about the doctors and the hospital that you are talking about.
关系代词充当表语
e.g. He is not the man that he used to be. = He is not what he used to be.
3、where引导的定语从句和地点状语从句
where引导的定语从句必须有先行词。如：place, school, city, house, room等
where不是修饰性名词，而是修饰其前整个句子，在句子中作地点状语。
e.g. Make a mark where you have any questions.
4、when, where, why引导的定语从句和同位语从句的区别
相同点：在两种从句中都可以充当状语成分
不同点：○1作关系副词引导定语从句时有跟它们含义相应的先行词
○2作关系副词引导定语从句时，可以改为“prep. + which”来引导
○3作连接副词引导同位语从句时没有与它们含义相应的先行词
e.g. I’ll never forget the day when (= on which) we met for the first time.
e.g. I have no idea when we met for the first time
在复合句中，修饰一个名词或代词的从句叫做定语从句；被定语从句所修饰的词叫先行词；定语从句必须放在先行词之后；引导定语从句的词叫关联词。
〔关联词〕
常见的关联词有关系代词that，which，who，whom，whose和关系副词where，when，why等。
〔种类〕
1．由that引导的定语从句
一般情况下that可指人或物，可以代替who，whom和which，在从句中作主语或谓语动词的宾语，但不能作介词的宾语。如：
The comrade that（who）is speaking at the meeting is an advanced worker．正在会上讲话的那个同志是个先进工人。
Is this the doctor that（whom）you talked about yesterday？这就是你们昨天谈论的那位医生吗？
The letter that（which）I received yesterday was from my father．昨天我收到的信是我父亲寄来的。
2．由who，whom和whose引导的定语从句
who在从句中作主语，whom在从句中作宾语，whose在从句中作定语。如：
This is the thief who stole my bike．这就是偷我自行车的那个贼。
He is the boy whom you wanted to find．他就是你想要找的那个男孩。
The girl whose mother is a doctor is waiting for you outside．妈妈是个医生的那个女孩在外面等你。
3．由which引导的定语从句
which指物，在从句中作主语或谓语动词的宾语。如：
The book which Mum bought me last week is called“Red Star Over China”．妈妈上周买给我的那本书名叫《西行漫记》。
The house which Lu Xun once lived in is now the Lu Xun Museum．鲁迅曾经住过的那所房子现在是鲁迅博物馆。
4．由where，when和why引导的定语从句
where在从句中作地点状语，when在从句中作时间状语，why在从句中作原因状语。如：
I will never forget the day when I joined the League．我永远忘不了我入团的那一天。
He will go back to the school where he studied next week．下周他要回到他曾经学习过的学校。
I don't know the reason why he quarreled with Zhang Lin．我不知道他同张琳吵架的原因。
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。
关系代词有：who, whom, whose, that, which等。
关系副词有： when, where, why等。
18.1 关系代词引导的定语从句
关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。
1）who, whom, that
这些词代替的先行词是人的名词或代词，在从句中所起作用如下：
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.
他就是我昨天见的那个人。（whom/that在从句中作宾语）
2) Whose 用来指人或物，(只用作定语, 若指物，它还可以同of which互换）, 例如：
They rushed over to help the man whose car had broken down. 那人车坏了，大家都跑过去帮忙。
Please pass me the book whose (of which) cover is green. 请递给我那本绿皮的书。
3）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：
A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有的繁荣。（which / that在句中作宾语）
The package (which / that) you are carrying is about to come unwrapped. 你拿的包快散了。(which / that在句中作宾语）
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