五、 连词
(一) 知识概要
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。
连词用法一览表
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.
(二) 正误辨析
[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.
[析] "虽然……但是"是中文中的常用结构，但在英文中用了"虽然"则不要用"但是",用了"但是"则不能再用"虽然",二者只可用其一。
[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.
[析] 并列句中常常在后面的句子中作一些省略，以免重复，但不是所有词都可作任意的省略的。当你连接的是两个系动词时，后面的那个系动词不可省略，也就是讲连接的部分不可省略。
[误] My father likes swimming and to collect stamps.
[正] My father likes swimming and collecting stamps.
[析] 由并列连词连接的两个部分要保持相等的语法结构。如是动名词则都用动名词，如用不定式则都应用不定式，这是初学者要注意的一点。
[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.
[析] 两个并列句中间不可用逗号连接，要用并列连词来连接。
[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.
[析] 宾语从句的连接词只能有一个不能重复使用。
[误] We will go both to Beijing and Shanghai.
[正] We will go to both Beijing and Shanghai.
[析] 用both…and…作连接词时，其相连接的部分结构也要相同。
[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.
[析] 主语从句的引导词that是不可省略的。这一点不要和宾语从句的引导词相提并论。
[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.
[析] 这里用when表达在一个动作的进行中，另一个动作突然发生了。正在进行的动作用一进行时态，而突然发生的动作用一般时态。
[误] While I heard the bad news I felt sad.
[正] When I heard the bad news, I felt sad.
[析] while不能表达一点儿的时间，即瞬时某一时间点。
[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.
[析] while在此处意为"而，然而".
[误] She sang when she walked along the dark street.
[正] She sang as she walked along the dark street.
[析] as用于句中时，其要点是强调两个动作的同时进行。这里用when虽然不能讲是语法上的错误，但则看不出来小女孩因独自走黑暗的街道因害怕而唱歌的心情。
[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.
[析] since引出的时间状语从句是表达了一个时间点，而这个时间点是主句动作的启始点，所以主句一般要用完成时态。
[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.