英语中哪些词可以连接句子，只有连词？那么请给我举比较常见的例子．ｗｈｅｒｅ，ａｓ　ｉｆ这种也可以连句子，它们本身是连词，还是怎样？书上写是从属连词，那么能否把连词的类别都告诉我，每个都举例子，要详细，谢了

第十二章连词
连词起连接单词、短语、从句或句子的作用。连词属于虚词，不能独立作句子的成分。
连词主要有两大类：并列连词和从属连词。
并列连词用于连接并列关系的词、词组或句子，常用的有and, but, or, for, so, both... and..., either...or..., neither...nor..., not only...but also...等。
从属连词用于引导从句，常用的有that, though, although, when, before, after, since , if, because, whether, till, until, so...that, so that, in order that, as soon as, as...as possible等。
一、并列连词
并列连词可以连接具有并列关系的单词、短语、句子和一些相同的成分。
并列连词可用于表示联合、转折、选择和因果等意义。
1表示联合意义
这一类连词经常使用的有and, both... and..., as well as, not only...but also..., n either...nor...等
(1)and:和，与
My brother and I enjoy swimming very much.
我哥哥与我都非常喜欢游泳。(并列主语)
All the pupils rushed out of the classroom and went to play on the playg round when the bell rang.
下课的铃一响，所有的孩子们都从教室里冲了出来跑到操场上去玩了。(并列谓语 )
Before going to school, Susan had two eggs and a glass of milk.
去上学以前，苏姗吃了两个鸡蛋，喝了一杯牛奶。(并列宾语)
He gave her a painting as a present, and she liked it so much.
他送给她一幅画作为礼物，她特喜欢它。(并列句子)
注意：“祈使句+and+陈述句”可以相当于“条件从句+陈述句”。
例如：Use your head and you will get a way .
(=If you use your head, you will get a way.)
动动脑筋，你就想出办法来的。
Go down this road to the crossing, and you'll find the cinema.
(=If you go down this road to the crossing, you'll find the cinema.)
顺这条路走到十字路口，你就会找到那家电影院。
(2)both...and... 既……又……，两者都……
Susan can speak both English and French.
苏姗既会说英语，又会说法语。
Both Tom and Peter are good players.
汤姆和彼得都是很好的运动员。
She both plays the piano and sings.
她既弹钢琴，也唱歌。
注意：①“both...and...”所构成的词组作主语时，其谓语动词须用复数形式。
Both you and I enjoy Peking Opera.
你和我都喜欢京剧。
②“both...and...”之中，and前后连接的词或词组要对等。(如上面例句，人对人，语言 对语言。)
③“both...and...”的否定句表示部分的否定。
She can't speak both English and French.
英语和法语，她不是都会说。(只会一种)
Both you and I don't enjoy Beijing Opera.
你和我并不都喜欢京剧。(只有一人喜欢)
(3)as well as 也…又…
The little girl is lively as well as healthy.
这个小姑娘既健康又活泼。
Lu Xun was a great writer as well as a doctor.
鲁迅是一名医生，也是一名大作家。
She is a virtuous wife as well as a nurse.
她既是一名护士，又是一个贤惠的妻子。
She as well as I is very fond of physics.
不仅我，她也非常喜欢物理。
Air,as well as water,is needed to make plants grow.
空气和水都是植物生长所必需的。
She as well as you will go climbing tomorrow.
不但你，她明天也要去爬山。
She plays guitar as well as sings
她既唱歌也弹吉他。
Susan is smart as well as beautiful.
苏姗又漂亮又聪明
注意：①当“as well as”连接两个主语时，其谓语动词要随“as well as”之前的主语变化。
②“as well as”在含义上侧重前者，而not only...but also...侧重后者。
(4)not only...but also...不但……而且……
Not only you but also she wants to go travelling.
不但你，她也想去旅游。(连接主语)
Her little brother can not only speak English but also write it.
她的小弟弟不但会说英语，而且会写。(连接谓语)
Mr. Smith lost not only his wallet but also his pa ssport.
史密斯先生不但丢了钱包，而且把护照也丢了。(连接宾语)
Jane is not only beautiful but also kind.
珍妮不但漂亮，而且为人善良。(连接表语)
注意：①“not only...but also...”作主语时，其谓语动词要随but also之后的主语变化。例如：
Not only you but also I am a doctor.
不仅你是，我也是一个医生。
②“not only...but also...”要连接对等的词或词组。(见上面例句，形容词对形容词，名词对名词)
③“not only...but also...”可以与“as well as”互相交换使用，但要注意其用法不同 。例如：
I as well as you am a doctor.
（=Not only you but also I am a doctor）
不仅你，我也是一名医生。
(5)neither...nor...既不……也不……;either...or...或……或……
I will visit either the Palace Museum or the Great Wall tomorrow. (either...or...为选择连词)
明天我不是去故宫就是去长城参观。
I will visit neither the Palace Museum nor the Great Wall tomorrow.
明天我既不去故宫也不去长城。
注意：①“either...or...”和“neither...nor...”所构成的词组作主语时，谓语动词随 or 或 nor 之后的主语变化。
Either you or he is wrong.
不是你，就是他是错的。
Neither you nor he is wrong.
你和他都没错。
②“either...or...”的否定句和“neither...nor...”都是全否定的含义。
She doesn't like either fish or me at.
鱼和肉她都不爱吃。
She likes neither fish nor meat.
鱼和肉她都不爱吃。
2表示转折的并列连词
这一类连词有：but, yet, while, however 等。
She tried hard to control the car, but she was unable to.
她竭力想控制住那辆车，但是她仍然做不到。
The truck was old but in excellent condition.
这辆卡车很旧，但是运行状况良好。
It is strange, yet it is true.
这件事虽然很奇怪，但却是真实的。
He sat there in class, yet his heart was left in the party.
他坐在那里上课，但心里却想着晚会的经历。
He was doing his homework while they were chatting.
他在做作业，而他们在闲聊。
While Mr. Li is cooking, his wife is entertaining the guests.
李先生在做饭，他的妻子在招待客人。
At last, however, she agreed with him.
最后，她还是同意了他的意见。
You lost a golden opportunity, however.
但是你失去了一次绝好的机会。
3表示选择的连词
这一类连词有：or, either...or..., otherwise 等。
Hurry up, or you'll miss the train.
快一点儿，不然你就赶不上火车了。
She must be joking, or she is mad.
她一定是在开玩笑，否则她就是疯了。
You can take the seat either by me or by the window.
或是坐我旁边，或是坐窗户旁边，你随便。
You must practise more otherwise you'll soon forget.
你必须多练习，不然你很快就都忘记了。
4表示因果意义的连词
这一类连词有：for, so, therefore等。
He was late again for the traffic jam.
由于交通阻塞，他又迟到了。
She tried very hard, so she succeeded in the singing competition.
她非常努力，所以在歌咏比赛中获得成功。
It rained, therefore the sports meet was postponed.
天下雨，所以运动会延期了。
二、从属连词
从属连词主要用于连接主句和各种从句。这些连词多数引导状语从句，还有一类引导主语从句、表语从句、宾语从句和同位语从句。
1引导时间状语从句的连词 before, after, when, while,
till, until, since, as soon as, as, whenever等。
引导时间状语从句，要特别注意时态的搭配。主句是一般将来时，从句要用一般现在时。
They are going to play football after school is over.
放学以后，他们打算去踢足球。
Before he became an artist, he was a worker.
他在成为一名画家以前，是个工人。
When I hurried into the cinema, the film had already begun.
当我赶忙进了电影院，电影已经开演了。
As (while) they were having supper, someone called on her.
正当他们吃晚饭时，有人来找她。
As soon as I got on the train, it moved.
我刚刚上了火车，车就开了。
She didn't agree to attend the meeting until I asked her a second time.
直到我第二次请她，她才同意来开会。
The boy was scolded whenever he failed to pass the exam.
每当这孩子考试不及格，都受到了责备。
He has been interested in music since he was a child.
他从小就喜欢音乐。
提示：由while引导的从句，所用的谓语动词必须是延续性的而绝不能使用点动词，如begin, go, come等。(见左边例句)
2引导地点状语的连词Where, Wherever
Can you tell me where he is now?
你可以告诉我他现在在哪儿吗?
Sit wherever you like.
你请随便坐。
3引导原因状语从句的连词because, as, since, now that 等。
He didn't come to her party because he was busy doing that experiment that day.
他那天没有去参加她的聚会，因为他正忙着做那个试验。
As there is no class tomorrow, they will go swimming.
由于明天没有课，他们想去游泳。
Since we know each other, I won't introduce.
既然大家互相都认识，就不用我介绍了。
Now that you have already known the result, you needn't wait her any more.
既然你已经知道了结果，你就不用再等在这里啦。
注意：在回答 why 问句时，只能用 because，而不能用 since, for 或 as 。
Why are you late again?
为什么你又迟到了?
Because I met a traffic jam on my way here.
因为我来这儿的路上，遇到了塞车。
4引导条件状语从句的连词if, unless, supposing,once, in case 等。这类从句要注意时态搭配，主句是一般将来时，从句用一般现在时。
If the weather keeps raining, the sports meet will have to be pos tponed again.
如果天气接连不断地下雨，运动会只能再延期了。
We'll miss the flight unless we hurry up.
除非我们快点，否则就赶不上这趟航班了。
Supposing she was ill and didn't come to your class, who would replace her?
假如她病了不来给你们上课，谁可以给她代课?
Once she reaches Shenzhen, she will call you.
一旦她到达深圳，她就会给你打电话的。
In case he comes, let me know please.
如果他来了的话，请告诉我一声。
5引导让步状语从句的连词though, although, even if, however 等。
Though (Although) I got there early, I wasn't able to get a ticket.
尽管(虽然)我很早就到达了那里，但仍没有买到票。
However early I arrived, I was unable to get a ticket.
无论我到那里有多早，我也买不到票。
Even if it was blowing hard, they came here specially to see you.
虽然外面刮着大风，他们专程来看你。
6引导目的状语从句的连词that, so that, in order that等。
The teacher spoke loudly so that she could be heard.
老师大声讲话，以便大家都能够听见。
In order that he could catch the early bus, he got up early.
为了能够赶上早班的公共汽车，他起得很早。
7引导结果状语从句的连词such...that, so...that等。
She is such a good teacher that all the students like her.
她是一位如此好的老师，以致全体同学们都非常喜欢她。
She drove so fast that it was difficult for her to control the car.
她把车开得太快以致她很难把握车的方向。
8引导比较状语从句的连词as, than, as...as,
more...than, the...the... 等。
The girl runs as fast as a deer.
这姑娘跑得像一只小鹿那样快。
This is more than I can accept.
这是我无法接受的。
Come to my office, the sooner the better.
到我办公室来一趟，越快越好。
9引导方式状语从句的连词as, as if (as though)
The old couple treated her as their own daughter.
那对老夫妻待她就像自己的亲生女儿。
She lookes at me as if I were a stranger.
她像看一个陌生人那样看着我。
It looks as if it was going to snow.
天看起来似乎要下雪。
10引导其他从句的连词
引导主语从句、表语从句和宾语从句的连词有三个：that, if 和 whether。
Whether he needs to have an operation is uncertain.
他是否需要做手术，还没有确定。(主语从句)
The problem is whether he needs an operation.
问题是他是否需要做手术。(表语从句)
Ask her if she needs to take some medicine.
问问她是否需要吃点药。(宾语从句)
I told him that he wasted the time.
我告诉他说，他浪费了时间。(宾语从句)
The plan should depend on whether it could be carried out.
这个计划取决于它是否可行。(作介词宾语从句)
注意：because，for，since和as的区别
1.because强调直接原因和因果关系，其从句的位置通常在主句的后面。
He was very happy because he passed the exam.
因为这次考试及格了，他非常高兴。
2.for强调间接原因和理由，或只是对主句中的事实作一下解释，该从句不放在句首。
I asked him to come out, for I had something urgent to tell him.
我让他出来一下，因为我有紧急的事情告诉他。
3.since 所表示的原因比 because 弱，比 as 强，不表示直接的或根本的原因，而是一种已知的或非常显然的理由。当其含义为“既然”时，放在句首。
Since everybody is here, let's start the meeting.
既然大家都到了，让我们开会吧。
as表示原因的意义最弱，所述原因只是附带说明。
You'd better stop here as it's too late.
天太晚了，你们最好就到这里吧。


参考文献：魔法英语初中语法
附件：第十二章连词.txt