连词是一种在句子与句子之间，短语之间以及名词等其他词语之间起连接作用的虚词，它不能单独作句子的成份。按其意义可分为并列连词和从属连词两大类。 并 列连词连接的双方是对等的。常有的并列连词有and, both…and, either…or, neither…nor， not only…but also, as well as等。但如果连接的两部分意义不趋向一致，意义有转折的并列连词有：but, however, while (而)，only (只不过)。还有表示选择关系的并列连词，如：or, or else, otherwise… 再有的是连接双方，互为因果，或表示前因后果的连词有：for, so, therefore (因此)，then等。 从属连词在初中范围内常常用来连接名词性从句，如：that, if, whether, 其次用来连接状语从句。其中有原因状语从句，常用的连接词有：when while, as, since, before, after, once, as soon as, until, till 连接条件状语的连词有：if, unless, as long as 等，而原因状语的连接词有because, since, as, now that (既然)。目的、结果、方式、比较、地点等状语从句的连接词有：so that, so…that, such…that, as…as, than, where… 它们在句子与文章中几乎无处不见。 具体用法见下表。
种类 功用 例句
并列连词 连接具有并列关系的 词 He knows neither English nor French.
短语 Are you going by bus or on foot?
分句 Mary was a good girl, but she had one shortcoming.
从属连词 引导： 状语从句 I'll do it as you told me.
You will be late unless you hurry.
连接代词和连接副词 主语从句 What he said proved true.
When we'll start has not been decided yet.
表语从句 This is why he didn't come yesterday.
That is where he lives.
宾语从句 The man asked me which I liked best.
I can't understand why she is so late.
关系代词和关系副词 定语从句 Nicotine is a drug that gets one into the habit of smoking.
He came last night when I was out.
[误] Both my parents are not here. They went to the concert just now.
[正] Neither of my parents is here. They went to the concert just now.
[析] 在英语中both一般用于肯定句中，如用于否定句中，其意义也不同于汉语，如：Both of us are not right. 在英语中应被理解为"我们俩不都对。"而Neither of us is right。 才能被理解为"我们俩无一正确"。
[误] He or his parents has some tickets for the film.
[正] He or his parents have some tickets for the film.
[析] 由or 连接两主语时，谓语动词应与相临近的那一个主语保持一致。
[误] You should study hard, and you won't pass the exam.
[正] You should study hard, or you won't pass the exam.
[析] or作为连词，这里的意思为"否则"。又如：Hurry up, or you'll be late for school.
[误] Though he is poor, but he is ready to help others.
[正] Though he is poor, he is ready to help others.
[正] He is poor, but he is ready to help others.
[误] Either you or I are on duty.
[正] Either you or I am on duty.
[析] either…or 连接两个主语时，其谓语动词与相临近的一个主语相呼应，这也叫作就近原则。类似的用法还有or, neither… nor, not only…but also等。
[误] Tom is our English teacher and teaching English in our school now.
[正] Tom is our English teacher and is teaching English in our school now.
[误] My father likes swimming and to collect stamps.
[正] My father likes swimming and collecting stamps.
[误] My father is reading a newspaper, I am doing my homework.
[正] My father is reading a newspaper while I am doing my homework.
[误] My father asked me that if I wanted to learn how to drive.
[正] My father asked me if I wanted to learn how to drive.
[误] We will go both to Beijing and Shanghai.
[正] We will go to both Beijing and Shanghai.
[误] Not only Mary but also her brothers is going to dance.
[正] Not only Mary but also her brothers are going to dance.
[析] 由not only… but also…连接两个主语时，其重点在其后面的那一个主语，所以谓语形式应采用就近原则。
[误] The teacher as well as his students are coming.
[正] The teacher as well as his students is coming.
[析] 由as well as 连接两个主语时，谓语动词与as well as 后面的名词无关，而与前面的名词相一致。
[误] Tom does not swim nor play football.
[正] Tom does not swim or play football.
[析] nor主要用于连接句子的对等连词，如在否定句中连接某一部分时要用or, 但要注意句子的含意，如：This animal does not like a cow or a horse. 这个动物既不像牛也不像马。This animal does not like a cow but a horse. 这个动物不像牛而像马。
[误] For there is no light in the classroom. The students must have gone home.
[正] The students must have gone home, for there is no light in the classroom.
[析] 由for引出的原因状语从句在使用时要注意不能将该从句置于句 首，而应置于主句之后，并在主句与从句之间加一逗号。更要注意的是because, as, since与for 4个表示原因的连词中because是因果关系，是最强的一个，而for是最弱的一个。有些语法书中干脆把for叫做并列连词
[误] My brother will pass the English exam is no question.
[正] That my brother will pass the English exam is no question.
[误] This map will show you how will you get to the hotel.
[正] This map will show you how you will get to the hotel.
[析] 名词性从句作宾语从句使用时，最重要的一点是要用陈述语句。特别要注意的是那些使用双宾语的动词，如：tell, ask, show…
[误] While the clock struch ten, all the lights went out.
[正] When the clock struck ten, all the lights went out.
[析] while是强调两个动作在同时进行中，如：While I am doing myhomework, my father is reading a newspaper. 而这里的when是"正当某某时刻"，"就在这一时间点上"，其重点强调在某一特定时刻某动作的发生。
[误] While I was walking along the street yesterday, I met an old friend.
[正] When I was walking along the street yesterday, I met an old friend.
[误] While I heard the bad news I felt sad.
[正] When I heard the bad news, I felt sad.
[误] After school some students play football, or others go to the library.
[正] After school some students play football, while others go to the library.
[误] She sang when she walked along the dark street.
[正] She sang as she walked along the dark street.
[误] I finished my homework until twelve o'clock last night.
[正] I didn't finished my homework until twelve o'clock last night.
[正] I did my homework until twelve o'clock last night.
[析] until用在句中时其含义是某一动作一直持续到某时结束，那么句中的动词则一定要用持续性动词，如果要用瞬间，或截止性动词时一定要用否定句式。因截止 性动作的否定式应看作是持续性的动作。如离开leave是瞬间动作，因一出门即为离开了，而不离开则是长时间的。
[误] I have studied English when I was twelve.
[正] I have studied English since I was twelve.
[误] Because he didn't study hard, so he didn't pass the exam.
[正] He didn't pass the exam because he didn't study hard.
[析] because 与 so在英文中两者不能并用的，只能在句中用其一。
[误] He was such excited that he could not speak.
[正] He was so excited that he could not speak.
[析] so与such的用法可以分为四种情况，①用于单数可数名词之前，其格式是such+不定冠词+形容词+单数可数名词，如：It is such a beautiful book that every child likes it. 也可以用so, 其格式是so+形容词+不定冠词+单数可数名词，如：It was so beautiful a book that every child likes it. ②在不可数名词前或可数名词复数前这时只能用such, 如：It is such good weather that we want to swim. 又如：They are such good students that they can pass the exam easily. ③在few, little， much, many 这4个字前只能用so而不能用such, 如：I have so much money that I can buy everything I want. ④当that前只有形容词或副词时，这时只能用so, 如：She is so beautiful that every one likes her. He ran so fast that I couldn't keep up with him.
[误] He got up earlier this morning so as to that he could catch the first bus.
[正] He got up earlier this morning so as to catch the first bus.
[正] He got up so earlier that he could catch the first bus.
[析] so…that与so that的用法有相同之处，那就是其后接从句，而so as to 其后要接不定式，即动词原形。这样的词组还有：in order to。
[误] I want to buy same stamp that you have.
[正] I want to buy the same stamp as you have.
[析] the same…as (that)这是个固定用法，在same前的定冠词是不能少的。而the same…that意为"我要的就是那一个"。而the same…as为"要的是和……一样的东西"。
[误] Before I do not give you the answer, I'll ask you some questions.
[正] Before I give you the answer, I'll ask you some questions.
1 We bought Granny a present, ___ she didn't like it.
A. but B. and
C. or D. so
2 Run quickly, ___ we'll miss the early train.
A. and B. but
C. so D. or
3 I'll give the book to him ___ he comes back.
A. since B. as soon as
C. before D. until
[析] as soon as 引出的时间状语从句应用一般现在时表示将来要发生的动作。
4 Don't cross the road ___ the light turns green.
A. when B. while
C. until D. as
[析] until应译为"直到……才"，因为前面的祈使句为否定句。又如：She did not go to bed until her mother came back. 应译为"直到她妈妈回来她才睡觉"。
5 Miss Gao has been a teacher ___ 1990.
A. before B. after
C. since D. in
[析] 因为主句为完成时，所以应用 since表示该动作的启始点。
6 - Which would you like better, tea ___ milk?
- Tea, please.
A. but B. and
C. or D. with
7 We love spring ___ there's beautiful flowers every where.
A. though B. but
C. or D. because
8 Please leave ___ 7∶00, then you'll be able to get ___ there earlier.
A. till, in B. from, /
C. before, / D. behind, to
9 The teacher didn't begin the lesson ___ all the students stopped talking.
A. until B. after
C. if D. because
10 Betty didn't go to see the film yesterday ___ she was ill.
A. but B. until
C. if D. because
11 You must start right now, ___ you'll miss the train.
A. for B. and
C. so D. or
12 ___ he is a child of six, he can read and write.
A. Whose B. If
C. Though D. Because
13 I like fish, ___ chicken, ___ eggs.
A. and, and B. and, with
C. /, and D. and, /
[析] 在有若干个名词或动词出现时，每一个词之间只用逗号连接，只在最后两个词之间加and。如：The old man passed the street, went into a shop and bought some food。
14 Take this dictionary with you ___ you may use it in class.
A. when B. in order to
C. but D. so that
[析] so that应译为"为的是"。本句句义为：带上字典，为的是在上课时可能有用。而in order to 其后应接动词不定式，如：Take this dictionary with you in order to use it in class。
15 I hope ___ will be fine tomorrow.
A. it B. what
C. whether D. when
16 ___ she was not well, I decided to go without her.
A. Though B. As
C. When D. Because of
[析] as这里应译为"由于"。全句意为：由于她不舒服，我决定不带她去了。而because of 其后不能接从句只能接宾语。如： Because of the heavy rain, we decided not to go。
17 My aunt bought me ___ many story books that I spent a lot of time them.
A. such…on B. such…in
C. too…in D so…on
[析] 因many前只能用so来修饰，所以只能选择D选项。而spend…on something 为在某事上花费时间或钱。如：She spent a lot of money on her clothes。
18 Mother was cooking ___ she ___ a knock at the door.
A. when, listen to B. while, listened to
C. while, heard D. when, heard
19 Speak slowly, ___ we can understand you.
A. and B. or
C. if D. because
20 You'll learn English well ___ you put your heart into it.
A. if B. so
C. until D. or
21 I won't let you in ___ you show me your pass.
A. until B. for
C. since D. because
22 She didn't go to school ___ she was ill.
A. why B. because
C. where D. but