句子是构成篇章的基本单位。要读懂一篇文章，首先要理解每个句子。同样，要写出一篇文章，首先要写好每个句子。一个句子最短的基本成分是“主+谓”，最长的基本成分是“主+谓+宾+补”。基本成分的修饰语为附属成分：定语—修饰限制名词或代词的单词﹑短语或从句；状语—修饰限制谓语﹑句子或句子里一部分的单词﹑短语或从句。
一、附属成分作定语
英语中的定语可分为限制性定语和非限制性定语。用来作定语的有：名词﹑数词﹑形容词﹑代词﹑副词﹑介词短语﹑非谓语动词和定语从句等等。
1. 限制性定语：单个词放在被修饰的词前面，短语和从句放在被修饰的词后面。
（1）名词﹑形容词﹑副词﹑数词﹑代词或介词短语等；
①She worked in a shoe factory.
②Please don’t be so cruel to a ten-year-old child like that.
副词作定语一般放在被修饰的词后面, 以表示位置的居多。如：
③Do you know the man over there?
④Poor Jack tottered toward a hospital nearby.
present, absent, a-开头的形容词和形容词短语作定语放在被修饰的词之后。可以理解成which /that / who +is（was） / are（were）引导的定语从句的省略。如：
⑤All the people present at the party were his supporters.
⑥I think he is the oldest man alive in the small town.
（1）非谓语动词（短语）,一般可转换成限制性定语从句。
①Let’s find a restaurant to have lunch in.
句中黑体部分可改为：where/in which we can have lunch
②The repairs cost a lot, but it’s money well spent.
句中黑体部分可改为：that/which was well spent
【注】 -ing形式作定语时只能用一般式， 表示与谓语动词动作同时发生，不可使用其完成式。如：
③Suddenly, a tall man driving a golden carriage seized the girl and took her away, disappearing into the woods.
句中黑体部分可改为：who/that was driving a golden carriage
④The flowers smelling sweet in the botanic garden attract the visitors to the beauty of nature.
句中黑体部分可改为：that/which smell sweet in the botanic garden
（3）限制性定语从句。
①We are living in an age when/in which many things are done on computer.
②Many people who had seen the film were afraid to go to the forest when they remembered the scenes in which people were eaten by the tiger.
2. 非限制性定语，一般放在后面，对中心词起修饰作用，而不对其进行限制。省略之后对句子意思的表达影响不大。
（1）名词﹑数词﹑形容词等短语，可理解为一个省略的非限制性定语从句。
①David, our English teacher, appreciated your idea much.
句中黑体部分可改为：who was our English teacher
②He was sent to France, a European country.
句中黑体部分可改为：which was a European country
（2）非谓语动词（短语）,一般可转换成非限制性定语从句。如：
The manager, making it clear to us that he didn’t agree with us, left the meeting room.
句中黑体部分可改为： who made it clear to us that he didn’t agree with us
（3）非限制性定语从句，常可转换成分词或并列句。如：
①John said he’d been working in the office for an hour, which was true.
句中黑体部分可改为：and it was true
②The famous basketball star, who tried to make a comeback, attracted a lot of attention.
句中黑体部分可改为：trying to make a co
