英语语法之连词

一、并列连词和从属连词的用法

连词是连结单词、短语、从句或句子的虚词， 在句子中不单独作句子成份，只能和其他词类一起作句子成分。

连词按其性质可分为：

1．并列连词 如：and, or, but, for,both .. and 、neither...nor 、either…or 、not only. ..but also 等， 连接并列的词与词，短语与短语，句子与句子。

如：Rice and potatoes are common foods. （词与词）

Today we can travel by plane. （短语与短语）

Many trees lose their leaves in winter, but evergreen trees do not. （ 句子与句子）

Are you going to have a picnic on Saturday or on Sunday?

关联连词是一类成对使用的连词

如：both……and……, not……but…….

not only……but also…… not only…but… as well

either……or…… neither……nor……

关联连词必须后接同样的语法结构。

如：Either the windows were opened or the door was opened.

2．从属连词 如：that, whether, when,while,as,after,before,until,if, because, though,although,than,as soon as等。如：Adam always finishes his homework before he plays football. She can’t go to school because she is ill today.

3．从属连词引导的从句不可以被断成一个句子。 如果断开，就错了。

如：When the alarm clock rang. （不完整）

4． though (although)引导让步状语从句，because引导原因状语从句， 所以though(although)不能和并列连词but ，because 不能和并列连词 so一起使用。 只能单独使用。

二、注意的要点

（1）表示选择关系的连词，连接的双方只取其一。常用连词有or, either...or, otherwise。例如：

1）You can go to Beijing either today or tomorrow.

2）You must get up early or you won’t catch the early bus.

（2）表示转折关系，连接的双方构成对比，意义上有转折。常用连词有but, however, while, only。例如：

1） His brother is fond of football while he likes basketball.

2） You can watch TV, but you must finish your homework first.

（3）表示联合关系，联合的双方是对等的，意义上趋向一致。常用连词有：and, both...and, neither...nor, not only...but also, as well as, together with。 例如：

1） To study English well, we need both diligence and careful.

2） That horse is not only the youngest among the five, but also runs the fastest.

（4）表示因果关系，连接的双方，互为因果，或者前因后果，或者前果后因。常用的连词有：for, so, therefore。例如：

1） It must have rained, for the ground is wet.

2） You are in the right, therefore they should support you.