根据英语词汇在英语句子中的地位和作用, 英语句子的成分可分为主语、谓语、宾语、宾语补足语、表语、定语、状语、同位语及独立成分等.其中,主语和谓语是句子的主要成分,一般情况下,一个句子不能缺少这两种成分.
1.主语：表示句子所要说明或描述的人或事物,一般由名词、代词或相当于名词的词组或句子充当,置于句首.如：
It’s getting cold. 天冷起来了.
Now everything is ready. 现在一切都准备好了.
The teacher is very kind to us. 老师对我们很好.
2. 谓语：说明或描述主语的动作、状态或特征,由动词或动词短语充当,位于主语之后.如：
Mother bought me a VCR. 妈给我买了一台录像机.
We have finished our work already. 我们已经完成了工作.
3. 表语：表示主语的身份、性质、状态和特征,一般由名词、形容词、或相当于名词、形容词的词、短语或句子充当,位于
连系动词之后,与连系动词一起构成句子的谓语.如：
Be careful! 小心!
He looks very angry. 他看上去很生气.
His job is looking after sheep. 他的任务是看羊.
4. 宾语：指动作所涉及的人或事物,一般由名词、代词或相当于名词的词组或句子充当,位于动词之后.如：
He wrote many plays. 他写了许多剧本.
She loves swimming. 她喜欢游泳.
5. 宾语补足语：用来对宾语进行补充和说明,一般由名词、
非谓语动词、形容词等充当.如：
He told us to stay. 他叫我们留下.
I’ve never seen her dancing. 我从未看见过她跳舞.
I found it difficult to refuse him. 我感到很难拒绝他.
6. 定语：对名词或代词进行修饰、限制或说明,一般由形容词、名词、代词、数词、介词短语、非谓语动词及句子等充当,位置可在所修饰的词之前,也可在所修饰的词之后(详见形容词一章).如：
It’s an interesting story. 那是一个有趣的故事.
Do you have time to help us? 你有时间帮助我们吗?
Who is the woman being operated on? 正在动手术的女人是谁?
7. 状语：用于修饰动词、形容词、
副词、短语或整个句子等,一般由副词、介词短语、非谓语动词短语或句子充当.如：
We like English very much. 我们非常喜欢英语.
Her uncle lives in Canada. 她叔叔住在加拿大.
She was lying in bed reading. 她躺在床上看书.
United we stand, divided we fall. 团结则存,分裂则亡.
8. 同位语：若两个语法单位指同一个人或事物,并且,句法功能也一样,那么,后一项称为前一项的同位语.如：
This is my friend Harry. 这是我的朋友
哈利.
We students should study hard. 我们学生应该努力学习.
9.独立成分：与句子其他成分没有通常的语法关系,如插入语、感叹语、呼语等,一般用逗号将它与句子隔开.如：
He’s a nice person, to be sure. 肯定他是一个好人.
Strange to say, he did pass his exam after all. 说也奇怪,考试他竟然通过了.
注：后两种初中不要求掌握
句子有这几大类 :
主谓
主谓宾
主谓宾宾补
主谓间接宾语直接宾语
主系表
这是基本的东西,先搞清楚后再搞其他高级的部分
第十五章 句子的结构
英语的句子,与汉语句子类似,按照语法结构也可分为三类,即简单句,并列句和复合句.那么有关这三种句型的详细信息,请看下面的讲解.
一、简单句
简单句只包含一个主谓结构,并且各个结构都是由单词或短语组成,不包含任何从句.简单句有五种基本句型.
1.主语+谓语(不及物动词)
The new term begins.
新学期开始了.
2.主语+谓语（及物动词）+宾语
The girl is learning to play the piano.
这个女孩在学弹钢琴.
3.主语+连系动词+表语
Susan is a student.
苏珊是个学生.
4.主语+谓语（及物动词）+间接宾语+直接宾语
He bought her a watch.
他给她买了一块表.
5. 主语+谓语（及物动词）+宾语+宾语补语
We all believed you honest.
我们都认为你是诚实的.
二、并列句(简单句+连词+简单句)
并列句是由两个或多个简单句连接而成的.其中的各个简单句并列平行,同等重要,相互之间没有从属关系,能够独立成句.它们之间要用连词连接.
并列句可分为四种：
1.表示相同关系
用连词或逗号、分号连接构成并列句.常用连词有：and, notonly...but also..., neither...nor...
Her father is a teacher and her mother is a doctor.
她的父亲是老师,母亲是医生.
Susan not only runs fast, but also jumps high.
苏姗不但跑得快,而且跳得高.
I could neither swim nor skate.
我既不会游泳,也不会滑冰.
I wouldn't see this film , it's boring.
我不想看这个电影,它令人心烦.
2.表示转折关系
常用连词有：but, still, yet,while, when等.
It was late at night, but he went on doing his homework.
夜已深了,但是他还在继续做作业.
She was busy cooking while they were watching TV.
她忙着做饭,而他们却在看电视.
The film is not perfect, still, it's good.
这部影片虽然不是无可挑剔,但还是好的.
3.表示选择关系
常用连词为：or, either...or.
Would you have tea or coffee?
你是喝茶还是咖啡?
The teacher wanted to see either his father or mother.
老师要见一下他的父亲或是母亲.
Either this road or that on e can lead you to that hospital.
这条路或那条路都通往那家医院.
4.表示因果关系
常用连词有for和so.
She soon fell asleep, for she was too tired.
她很快就睡着了,因为她太累了.
We hurried to the railway station, for there was little time for the train toleave.
我们急忙赶往车站,因为火车很快就要开了.
It was raining harder and harder, so we had to stay at home.
雨下得越来越大,所以我们只得呆在家里.
The teacher asked Susan to go, so she went.
老师让苏姗到她那去,因此她就去了.
注意：1、. 在”
祈使句+and/or+陈述句”结构中,当前后两部分间为承接关系时,用and;前后意思为相反关系时,用or.可将前面的祈使句转换成由if引导的条件状语从句,但必须将and 或or 去掉.
如: Hurry up, and we’ll be there in time.= If wehurry up, we’ll be there in time.
2. because和so; although, though和but不能连用
(二)并列连词和连接性副词的区别
引导并列结构的并列连词有and, or, but, so, for, nor等,并列连词包括关联连词both…and, either…or,neither…nor,not only…but also, as well as, as much as等.并列连词也包括连接性副词,如however, hence, therefore, besides, moreover, yet, anyway,
consequently, still, nevertheless, all the same等.但并列连词和连接性副词存在着如下的区别：
1. 位置上的区别
连接两个独立的分句时,并列连词的位置只能放在它所引导的分句句首,前面通常有逗号：
Lopez left For Woodside(美新译西州一城市)the day before yesterday, and he won't be back till the end of the month.
I must work harder, for I still have a long way to go.
Pay him back, or he will bring a suit against you. (快还他钱,不然他要向你起诉.)They all went, but I didn't(go).
连接性副词的位置较灵活,既可放在句首,也可位于句中或句末、但以置于句首居多：
Father is ill; therefore ,he doesn't go to work today.
置于句首
Father is ill; he, therefore, doesn't go to work today.
置于句首
Father is ill; he doesn't go work today, therefore.
置于句末
2. 用法的区别
两个并列连词不可以连用：
Oscar and I go to the club every Saturday evening, and but we play bridge there. (根据句意,应把but划掉.)
但并列连词却可以和连接性副词连用：
He is not in favor of the plan, and yet he raised no objection.
三、复合句(主句+连词+从句)
包含一个主句,一个或一个以上的从句的句子叫复合句.从句从属于主句并充当主句的某一成分,如主语,表语,宾语,定语,状语等.
(一)、引导名词性从句的连接词
分类
引导名词性从句的连接词可分为三类：
连词（5个）：that（
宾语从句或表语从句中that有时可以省略）
whether,if （均表示“是否”表明从句内容的不确定性）
as if ,as though （均表示“好像”,“似乎”）
以上在从句中均不充当任何成分
连接代词（9个）：what, whatever, who, whoever,whom, whomever, whose, which, whichever
连接副词（7个）：when, where, how, why, whenever, wherever, however
不可省略的连词：
1. 介词后的连词
2. 引导主语从句和同位语从句的连词不可省略.
That she waschosen made us very happy.
We heard the newsthat our team had won.
比较
whether与if 均为"是否"的意思.但在下列情况下,只可用whether：
1. whether引导主语从句并在句首
2. 引导表语从句
3. whether从句作介词宾语
4. 常与 "or not" 连用；if 则不可.
5. 引导同位语从句
Whether he willcome is not clear.
大部分连接词引导的主语从句都可以置于句末,用 it充当形式主语.
It is notimportant who will go.
It is still unknown which teamwill win the match.
1.主语从句
主语从句就是从句作主语.它可作谓语动词的主语,也可作分词的主语.主语从句有三种：
(1)由that引导：
It is impolite（ that you talked so loud inthe restaurant）---指代it的内容
你们在餐馆那么大声音说话是极不礼貌的.
It is a great surprise that she won the champion.
她得了冠军,真是令人惊异.
(2)由what, whatever和whoever等代词引导：
What she said just now is correct.
她刚才说的话很对.
What caused the air disaster is under the investigation.
究竟是什么导致了这次空难,正在调查.
Whatever you have seen must be kept in your mind.
不管你看到什么,都要记在心里.
Whoever breaks the world record will get one million yuan as an a ward.
任何打破世界纪录的人将得到一百万元奖金.
(3)由连接副词whether, how, when,why, where引导：
When the sports meet will be held isn'tdecided.
什么时候开运动会还没有定下来.
Whether she can pass the exam is not sure.
她是否能够通过考试还没有把握.
How he arrived there is unknown to anybody.
他是如何到达那里的,没有人知道.
Why the fire broke out here in the workshop remains a mystery.
车间这里为什么会发生火灾仍是个谜.
注意：当主语从句过长而谓语较短时,通常用代词it作形式主语,而把从句放在句尾.
It remains a mystery that the air disaster took place that day.
那天发生的空难仍然是个谜.
It is uncertain whether we'll attend the meeting or not .
我们是否参加那个会议还没有确定.
2.宾语从句
这类从句常是这种结构：主句+引导句+从句,从句中始终用陈述语序.
(1)由that引导(通常that可以省略)
She is very sure that she can work out the problem.
她确信她能解出这道题.
She told me that she could finish it herself.
她跟我说她可以自己完成这件工作.
(2)由what, who, which等关系代词引导
We don't understand what you said just now.
我们不明白你刚才说的话.
Tell me which you want?
告诉我你要哪一个?
Do you know who is the man over there?
你知道那边那个人是谁吗?
(3)由how, when, why, where引导宾语从句
They wanted to know when the building would be set up.
他们想要知道这座楼房何时建成.
Will you please tell me how I can get to the park?
请告诉我怎么走才能到公园好吗?
I wonder where she is now.
我想知道她现在在哪儿?
I don't know why you dislike physics.
我不知道为什么你讨厌物理.
(4)一些形容词之后所接的句子也是宾语从句.这些形容词有：glad, sorry, sure , afraid,worried, angry, aware, confident等.
I'm glad that you've helped me a lot.
很高兴你给我这么大的帮助.
We are confident that we can beat them.
我们有信心打败他们.
The father was angry that his son failed to pass the maths exam.
这位父亲对他的儿子数学不及格很恼火.
I'm not sure if she has finished the painting.
我不清楚她是否完成了那幅作品.
注意：当宾语从句过长时,可用it作形式宾语而将从句放在句子后面.
She thought it pity that I had missed the chance.
她认为我错过了那个机会非常可惜.
I found it very easy that I worked out the problem .
我觉得很容易地就做出了这道难题.
The manager made it clear that your idea was impossible .
经理已明白地指出你的想法不能实现.
3.定语从句
以从句的形式修饰或限定主句中的名词、代词、短语等的句子,叫作定语从句.
定语从句通常用关系词(关系代词和关系副词)把它与主句连接起来.它在句中所修饰和限定的词或短语称为先行词.
引导定语从句的关系代词有：who(指人,在从句中作主语或宾语),whom(指人,作宾语) ,whose(指人,作定语),that(可指人或物),which(指物).
引导定语从句的关系副词有：when(指时间),where(指地点),why(指原因).这些关系副词相当于(介词+which).例如：
when=in(on,at,during)+which
where=in(at,to)+which
why=for which
(1)关系代词在从句中作主语、表语、宾语或定语；关系副词在从句中作状语.
作主语：Thewoman who is talking to the teacher is her mother.
正在跟老师说话的那个女人是她的母亲.
The boy who played the piano on the stage yesterday is Mr. Li's s on.
昨天在台上弹钢琴的那个男孩儿是李先生的儿子.
作表语：Chaplinwas a great actor whose name is well known all over the world.
卓别林是一位闻名于全世界的伟大的演员.
作宾语：Do you know the man whose sonis your schoolmate?
你认识那个他的儿子是你同学的男人吗?
作宾语：Iam looking for the bike (that) I put here yesterday.)
我正在找昨天我放在这里的自行车.
These are the reference books (that) I bought for you yesterday.
这些是我昨天给你买的参考书.
作状语：
指时间：
Jack wasted much time on those days when he was in the middle school.
杰克上中学的时候,浪费了许多时光.
It was in 1937 when Japanese soldiers broke into the city Beiping.
日本鬼子闯入北平城是在一九三七年.
指地点：
This is the place where the composer Beethoven was born.
这就是作曲家贝多芬出生的地方.
Have you been to the seaside where we can enjoy swimming?
你去过那处我们可以尽情游泳的海滨吗?
指原因：
Do you know (the reason) why she was so sad?
你知道她为什么这样伤心吗?
Who can tell me why it's so unfair?
谁能告诉我为什么老天爷如此不公平?
That's(the reason)why he was absent.
这就是他缺席的原因.
注意：①当先行词被first,last这类词或最高级修饰时,一律都用that而不用which或who (不管先行词是指人还是物).
This is the most beautiful picture that Ihave ever seen!
这是我所看见过的最美的画!
I'm the only one that you can rely on.
我是你唯一能够依靠的人.
②当先行词为all,no,any,only,little,much,something,anything,nothing,everything等不定代词的时候,必须用that作引导词引导定语从句.
There is nothing that she can say to you.
她对你没有什么话可说.
She is not interested in anything (that) he has told her.
她对他告诉她的任何事情都不感兴趣.
(2)介词前置的定语从句关系代词which和whom还可以作介词的宾语,这时要把介词放在整个定语从句的前面.
Is this the school in which you studies?
(in which=where)
这是你上学的学校吗?
The man on whom the whole family rely died in a traffic accident yesterday.
那个全家人依靠的顶梁柱昨天死于一场交通事故.
关系代词that和关系副词when,where等都不能作介词的宾语.
The house in which they are living was built 50 years ago.
他们现在正居住的房子是50年以前建的.(不能说：Thehouse in that they are living w as built 50 years ago.)