形容词以及形容词性从句
形容词的语法功能：定语、表语、补语、状语。 She is beautiful.
We find the NETEM difficult. The girl stood there, full of fear. He is a handsome boy.
He is a boy who is handsome.
注意：
（1）一般情况下形容词作定语时，与汉语习惯一样，位于被修饰词之前（即作前置定语）。
Almost all the residential, commercial and industrial current in the world today is alternating current.
而在下列情况下，形容词常常或一定要作后置定语： a. 以-able或-ible结尾的一些形容词（如：available，obtainable，achievable，attainable，receivable，usable，possible，responsible等）或corresponding，total，similar等作后置定语，主要表示强调。如：
Even in this case, there are two directions possible. b. 少数形容词一般只作后置定语，如：present（“存在的，在场的”），whatever（在前面已经有no或any修饰的名词后，表示“任何的”）， else（用在疑问代词或不定代词后面，表示“其他的”），concerned（“有关的”），alone（“仅仅，单单”）等。如： In this case, no rotation whatever will result.
c. 修饰something，anything，everything，nothing，somebody，nobody，anybody，everybody，someone，anyone，everyone，no one等不定代词时，形容词必须后置。如： Now computers are nothing mysterious.
d.“副词（或数量状语）+形容词”作后置定语 Let us consider two parallel wires 50 cm long. This shows a situation a bit more complex.
（2）形容词短语的形式如下：
a. 形容词+介词短语，这一类形容词短语数目最多，如： similar to，dependent on，capable of，familiar with，different from b. 形容词+动词不定式，如：
able to，ready to，necessary to，too…to…， free to c. 形容词+状语从句（尤其是比较状语从句） This is a number larger than 1.
d. 由并列连词连接的两个或多个形容词
（3）当形容词短语作状语时，其逻辑主语一般是句子的主语，有时则是其后面或前面的整个句子。位于主语之前，往往充当表示原因，条件，时间，对主语的附加说明，或对后面句子进行评注的状语。位于句尾，往往是对其前面句子主语或整句的一种说明，也可以作方式状语。
Accurate in operation and high in speed, computers can save man a lot time and labor. The conductor is moving parallel to the magnetic field.
定语从句
定语从句的定义：
定语从句是指在句中作定语成分，修饰主句中的名词或代词的从句，其中被修饰的名词或代词被称为先行词。当关系代词作定语从句的主语时，其后的谓语动词的人称和数取决于先行词的人称和数。
定语从句的结构：
定语从句一般位于先行词的后面：先行词（被修饰的名词或代词）+关系词（引导词） He who laughs last laughs best.
Many of life’s problems which were solved by asking family members, friends or colleagues are beyond the capability of the extended family to resolve.
George W. Bush junior, whose IQ was said to be lower than 85, was elected as the American president, which surprised the world.
定语从句的种类：
从修饰的语义紧密与否的角度可分为限制性定语从句和非限制性定语从句，其实从结构上来看就是看被修饰的词与后面的引导词之间是不是有一个逗号隔开。如：
He studies hard at school when he was young, which contributes to his success in later life.
1. 严格来说，直接影响全句确切含义的定语从句被称为限制性定语从句，如果把它删掉的话，原句的意思就不完整了。从形式上看，这种定语从句与被修饰词之间没有用逗号分开。如：
This is the house which we bought last month.
2. 只起到进一步说明作用的定语从句，被称为非限制性定语从句。从形式上看，它与被修饰词之间由逗号分开，如：
The house, which we bought last month, is very nice.
a. 当先行词由专有名词或物主代词和指示代词所修饰时，其后面的定语从句通常是非限制性的。如：
Charles Smith, who was my former teacher, retired last year. My house, which I bought last year, has got a lovely garden. This novel, which I have read three times, is very touching. b. 非限制性定语从句又可以分为两类：
修饰其前面某个名词或代词的非限制性定语从句。
修饰整个主句（有时修饰其一部分）的非限制性定语从句，如： He seems not to have grasped what I meant, which greatly upset me. Liquid water changes into vapor, which is called evaporation.
c. 关系代词that和关系副词why不能引导非限制性定语从句。
定语从句的引导词
定语从句的引导词分为关系代词和关系复习两类。
1. 关系代词：常见的关系代词有以下几个。
that：用于指人或事物，在从句中主要作主语和宾语，个别情况下还可以作介词宾语（这时介词一定要位于从句的末尾）和表语。that一般不能用来引导非限制性定语从句。
which：只用于指代事物，它在从句中主要作主语，宾语和介词宾语，个别情况下也可以作表语或定语。
whose：用于指代人或者事物，它在定语从句中只能作定语，表示所属，译成“其”。 who：只能用于指代人，它在从句中作主语（作宾语时要用whom）。
as：可以指代人或事物，它在从句中主要作主语和宾语，其本身有词义，译成“正如。。。那样”。
2. 关系副词
关系副词在定语从句中主要作状语，常见的关系副词有以下几个。
where：表示地点，场合，情况等（如：place，situation，degree，case等）
when：用来修饰表示时间的名词（如：time，moment，instant，cycle，occasion，point等）。 why：用来修饰表示理由的名词（主要是reason一词）。 as：主要出现在in the same way/manner/direction as…表达式中。
that：主要用来替代when，where，why以及少数几个“介词+which”结构。
注意：
1. 不要把上面的两类关系词与引出疑问句的疑问词，引导状语从句、名词性从句的引导词相混淆，它们各自的名称，作用及译法都是不同的。
2. 关系词具有双重作用。关系词在定语从句中一定要充当某一句子成分。关系词一定要指代主句中的某个名词或代词（甚至整个主句或其一部分），也就是说，它所引导的定语从句也一定是修饰那个人或那个事物的。所以每当遇到一个定语从句时，关键一点就是要首先找到先行词，然后尽力找出这个关系词所指代的词，关系词代替哪个词，定语从句就修饰那个词，定语从句通常就是从那个词后面开始的。
（1）who，whom，that
这些词代替的先行词是人的名词或代词，在从句中作主语或宾语。如： Is he the man who/that wants to see you? He is the man whom/that I saw yesterday.
The one who was talking to you a minute ago is a professor.
(2)whose表示所属格，它后面必须接一个名词，不能单独使用。 They rushed over to help the man whose car had broken down. Please pass me the book whose cover is green.
(3)which, that 所代替的先行词是事物的名词或代词，在从句中作主语、宾语等。作宾语时常可省略。如：
A prosperity which/that had never been seen before appears in the countryside. The package (which/that) you are carrying is about to come unwrapped.
(4) 关系副词when，where和why的含义相当于“介词+which”结构，因此常常和“介词+which”结构交替使用。如：
There are occasions when (on which) one must yield. Beijing is the place where (in which) I was born.
Is this the reason why (for which) he refused our offer?
The day when we stop learning is the day when we die.
Literature is the place where the past meets the present to contemplate the future. 翻译：文学是一个殿堂，在那里，过去与现实相衔接，为的是更好地思考未来。
（5）that代替关系副词，可以用于表示时间，地点，方式，理由的名词后面取代when，where，why和“介词+which”引导的定语从句，在口语中that常被省略。如： His father died the year (that/when/in which) he was born.
He is unlikely to find the place (that/where/in which) he lived forty years ago.
注意：
对关系代词和关系副词的判断
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；而不及物动词则要求用关系副词。如： This is the mountain village where I stayed last year. I will never forget the days when I worked together with you. 判断改错：
This is the mountain village where I visited last year.
I will never forget the days when I worked together with you. This is the mountain village (that/which) I visited last year.
I will never forget the days (that/which) I spent in the countryside.
习惯上总把表地点或时间的名词与关系副词where，when联系在一起。以上两句错在关系词的误用上。
方法二：准确判断先行词在定语从句中的成分（主、宾、定、状、表），也能正确选择出关系代词或关系副词。
Is this museum_____ you visited a few days ago?
a. where b. that c. on which d. the one
Is this the museum_____ the exhibition was held? a. where b. that c. on which d. the one
在例1中，定语从句所缺部分为宾语，而where，on which 都不能起到宾语的作用，that只能作定语从句的宾语，只有the one既作了主句的表语，又可作从句的宾语，可以省略关系代词。
在例2中，定语从句中主、谓、宾俱全，从句部分引导词为句子的状语表示地点，可用关系副词where，也可用in which表示in the museum。
关系词的选择要依据先行词在从句中所作的成分，先行词在从句中作主、定、宾、表时，选择关系代词（that，which，whose，who，whom）；先行词在从句中作状语时，应选择关系副词（where，when，why）。
关系代词that的用法： 1. 不用that的情况
a. 引导非限制性定语从句时
The tree, that is four hundred years old, is very famous. （错） b. 介词后不能用，且介词在定语从句开首
We depend on the land from which we get our food.
We depend on the land that/which we get our food from.
2. 在修饰事物的限制性定语从句中，若关系代词在从句中作主语或宾语时，that和which的用法在一般情况下是完全一样的，因此它们可以互换。但是，在下列场合下，只能用that而不能用which：
a. 当先行词为something，everything，anything，nothing，all，much，many，some，any，
few，little，none，one等不定代词，定语从句的引导词多为that。
I am interested in all that you have told me. This reference book contains little that is useful.
Every new generation is different from the one that preceded it.
Our democratic and populist urges have driven us to reject anything that smells of elitism. 我们对民主以及平民主义的迫切要求促使我们摒弃任何带有杰出人物统治论意味的东西。 In the present organization of the Olympics there is far too much that encourages aggressive patriotism.
在当前奥运会的组织中，有太多鼓励攻击性的爱国主义的东西。
b. 当先行词由the only，the very，the last，the same, no, any等词修饰时，定语从句引导词多为that。
Food isn’t the only problem that such a population explosion presents. This is the very T-shirt that I want to buy.
c. 先行词被序数词修饰时，定语从句引导词多为that。
The first place that they visited in Guilin was Elephant Truck Hill.
d. 当先行词由形容词最高阶修饰时，定语从句引导词多为that。 This is the best article that has ever been written on the subject.
e. 若先行词有两个，一个指人，一个指物时，关系代词只能用that。 He talked about the teachers and schools that he had visited.
关系词的译法
1.如果定语从句（主要是限制性的）比较短，则翻译时一般就直接把定语从句译在被修饰词的前面。这时关系词往往只要在从句末尾译成一个“的”字即可。 The instrument that we often use is very good in quality. A target is the object whose position is to be determined.
2. 如果定语从句比较长，在不影响句子原意的前提下，翻译时可以把定语从句译成单独的一句，这时一定要把“关系词”译成所代的那个词，同时还应适当加些“润滑”词（非限制性定语从句则多数应译成单独的一句）。
Each mass exerts on the rod a force which is equal and opposite to the force that the rod exerts on in.
Rockets perform best in space, where there is no atmosphere to impede their motion.
关系词的省略
在限制性定语从句中，有时关系词可以省略。
判定定语从句中的关系词是否被省略的方法：如果一个句子中有两个或多个没有并列关系的谓语，且有两个紧挨着的、看起来互不相干的名词（或代词，或一个名词一个代词），那么这个句中可能就有省略了关系词的定语从句。
关系词可以省略的场合主要有以下三种：
1. 关系代词that或which作及物动词（不管是谓语还是非谓语）的宾语时可以省略，这是最常见的情况。
The unit of voltage we shall use is volt.
The voltage we can use this meter to measure is a DC voltage. 2. 关系代词which在从句中作单个介词的宾语，而且“介词+which”在从句中作状语时which可以省去（作定语时是绝不能省略的）。其条件是一定要把介词置于从句末尾，只有在这种