句子成分是英语学习里很重要的一部分，能清楚分清句子成分、熟悉各成分的作用、由什么词类充当可以很好地帮助我们理解英语句子，解题的时候思路也更清晰。
下面我们分别来讲解英语句子里面主要的九大句子成分：主语、谓语、宾语、定语、状语、补语、表语、同位语、独立成分。我们将从各句子成分的概念、充当各句子成分的常用词类、以及对应的例句来帮助大家更好地理解英语句子成分。
(一) 主语
主语是一个句子的主体，一般位于句首。它常由以下词类充当：
名词 A tree has fallen across the road.
代词 He told a joke but nobody laughed.
不定式 To become a doctor is his dream.
动名词 Smoking is bad for you.
主语从句 Whenever you are ready will be fine.
数词 Three is enough.
名词化的形容词 Old and young walked side by side.
名词化的过去分词 The disabled are to receive more money.
句子 “How do you do?” is a greeting.
(二) 谓语
谓语用来说明主语做什么或者怎么样。一般由动词、动词短语（普通动词短语、助动词+主要动词、情态动词+主要动词）充当。
He worked hard all day today.
The plane took off at ten o’clock.
I am reading.
You can do it if you try hard.
(三) 宾语
在主动语态里，宾语一般是动作的承受者，一般位于及物动词、介词之后。它常由以下词类充当：
名词 Paper catches fire easily.
代词 Where did you buy that?
不定式 Remember to buy some stamps, won’t you?
动名词 He stopped smoking last week.
宾语从句 I wondered how old he was.
数词 If you add 5 to 5, you get 10.
名词化的形容词 I shall do my possible.
名词化的过去分词 He never did the unexpected.
句子 He said, “You are quite wrong.”
(四) 定语
用来说明名词（代词）品质或特征的词。它常由以下词类充当：
形容词 She is a good musician.
名词 He found a baby girl
代词 Your hair needs cutting.
数词 There is only one way to do it.
副词 The life today is different from the life in the past.
不定式 That’s the way to do it.
动名词 He has a good learning method.
分词 There is a sleeping child on the bed.
介词短语 This is a map of China.
(五) 状语
状语修饰动词、形容词、副词、全句。
He speaks the language badly but reads it well.
His English is very good.
The old man sat quite comfortably on the chair.
Fortunately, she found the pen she lost.
状语常由以下词类充当：
副词 If I remember rightly, we turn left now.
不定式 At the top we stopped to look at the view.
分词 I began to get the shakes just thinking about the test.
介词短语 At the end of the film, I was in tears.
从句 Even if she laughs at him, he likes her.
名词 The Party teaches us to serve the people heart and soul.
形容词 She hurried up the steps, nervous and pale. (脸色苍白)
数词 I hate riding two on a bike.
(六) 补语
用来补充主语和宾语的意义。
（1）主语补语
它常由以下词类充当：
形容词 He get off the bench very nervous.
名词 He was called Oliver Barret.
不定式 He was seen to go upstairs.
分词 He came home quite changed.
介词短语 He came home out of humor（心情不好）.
（2）宾语补语
它常由以下词类充当：
形容词 I found the book very interesting.
名词 They named the child Jimmy.
不定式 Father will not allow us to play on the street.
分词 I have friends coming.
介词短语 I found everything in good condition.
(七) 表语
表述主语的特征、状态、身份等，位于连系动词之后，构成系表结构。它常由以下词类充当：
名词 It’s a pity that we shall be a little late.
代词 That coat is hers.
形容词 The well is dry.
副词 My day’s work is over.
不定式 All I could do is to wait.
表语从句 That is what he means.
数词 I’ll be twenty-four in May.
分词 I was so much surprised at it.
介词短语 She is in good health.
(八) 同位语
当两个指同一事物的句子成分放在同等位置时，某个句子成分被用来说明、解释另一句子成分，这个句子成分就是另一个句子成分的同位语。它常由以下词类充当：
名词 We have two children, a boy and a girl.
代词 They all wanted to see him.
数词 Are you two ready?
Of短语 The ship has a length of 120 meters.
同位语从句 The news that we are having a holiday tomorrow is not true.
不定式 His decision to become an actor was not supported by his family.
动名词 The first plan, attacking at night, was turned down.
(九) 独立成分
与全句没有语法关系的句子成分叫句子的独立成分。它常由以下词类充当：
插入语 This view, however, seems to be wrong.
呼语 Goodbye, everybody!
感叹语 Oh, John, will you come into my room, please?
阅读了上面的内容之后，相信大家对英语句子成分有了初步的了解。不断探索适合自己的英语学习方法，再加以坚持，相信你能取得不小的进步哦！