第一章 · 连词

第一章-连词

第一章 基础语法—5.连词

一、连词的定义及分类

用来连接词、短语，从句或句子的词叫连词。连词是一种虚词，在句中不能单独使用。连词可分为两类：并列连词和从属连词。

并列连词

用来连接具有并列关系的词，短语或句子，常见的并列连词有：

表并列关系的and ,both……and, not only……but also, neither……nor等

表选择关系的or .either……or等

表转折关系的but, while等

表因果关系的for, so ,because等

从属连词用来引导从句，可分为引导状语从句和引导名词性从句的连词。

常见的引导状语从句的从属连词有：

引导时间状语从句的after, before, when, while, as, until, till, since, as soon as等。

引导条件状语从句的if, unless等。

引导原因状语从句的because, as, since等。

引导目的状语从句的so that, in order that等。

引导让步状语从句的though, although, even if等。

引导结果状语从句的so that, so…that, such……that等。

引导比较状语从句的than, as……as等。

引导名词性从句的连词主要有that, if ,whether等。

它们用于引导主语从句、表语从句、宾语从句和同位语从句。其中that 不仅不充当句子成分，而且没有词义，在句中只起连接作用；而if, whether虽不充当句子成分，但有词义，表示“是否”。

Little did he care whether we live or die.

他一点也不管我们是死是活。

He claimed that the newspaper report was a libel.

他声称报纸上的报道是一种诽谤。

二、常用连词的用法辨析

while ,when ,as

这三个连词都可引导时间状语从句，但用法有所不同。

当某事正在进行的时候，又发生了另一件事。while, when ,as都可用来引导表示“背景”的时间状语从句。

As/when/while I was walking down the street I noticed a police car.

当两个长动作同时进行的时候，最常用的是while.

While mother was cooking lunch, I was doing my homework.

当两个动作都表示发展变化的情况时，最常用的是as.

As children get older, they become more and more interested in things around them.

当两个短动作同时发生时，或表示“一边……一边……”时，最常用as.

Just as he caught the fly, he gave a loud cry.

She looked behind from time to time as she went away.

当从句的动作先于主句的动作时，通常用when.

例如：

When John arrived I was cooking lunch .

as, because ,since ,for

这四个词都表原因，但用法有区别。

如果原因构成句子的最主要部分，一般用because.因此，because引导的从句往往放在句末。

I stayed at home because it rained .

如果原因已被人们所知，或不如句子的其他部分重要，就用as或since. since比as稍微正式一点。这两者引导的从句一般放在句子的开头。

As he wasn't ready ,we left without him.

Since I have no money ,I can't buy any food.

for用来补充说明一种理由，因此，for引导的从句几乎可以放在括号里。for引导的句子不放在句子的开头。

I decided to stop and have lunch——for I was feeling quite hungry.

if ,whether

都可作“是否”讲，在引导宾语从句时一般可互换。

I wonder whether(if) you still study in that school.

I don't know whether(if) he likes that film.

在下列情况下，只能用whether,不能用if：

引导主语从句时

Whether he will come to the party is unknow.

引导表语从句时

The question is whether I can pass the exam.

在不定式前

I haven't made up my mind whether to go there or not.

so……that, such……that

so……that中的so是个副词，其后只能跟形容词或副词，而such……that中的such是个形容词，后接名词或名词短语。

I'm so tired that I can't walk any farther.

It was such a warm day that he went swimming.

either……or， neither……nor, not only……but also

这三个连词词组都可连接两个并列成分。当它们连接两个并列主语时，谓语动词要随相邻的主语变化（就近原则）。

Either you or he is wrong.

Neither he nor his children like fish.

Not only the teacher but also the students want to buy it.

although, but

这两个连词不能用在同一个句子中。

Although he is over sixty, he works as hard as others.

He is over sixty ,but he works as hard as others.

because ,so

这两个连词同样不能用在同一个句子中。

Because John was ill, I took him to the doctor.

John was ill ,so I took him to the doctor.