（一）连词概述
连词是连接单词、短语或句子的一种虚词。在句中不单独作句子成分。历年中考中常考并列连词 and， but， neither… nor；从属连词 now that， though， when。所以了解状语从句和宾语从句的真正意义有助于正确使用从属连词。
（二）基础知识梳理
1．并列连词用来连接彼此并列的词、短语或句子。并列连词有 and， or， but， so， for， nor等。
2．关联连词有 both… and， either… or， neither… nor， not only… but also， as well as， as much as等。
3．连接性副词有 however， therefore， besides， yet， anyway， still， all the same等。
4．并列连词和连接性副词存在以下的区别：
1)连接两个独立的分句时，并列连词的位置只能放在它所引导的分句的句首，前面通常有逗号。如：
I must work hard, for I still have a long way to go.
They all went, but I didn't go.
2)连接性副词的位置比较灵活，句中、句首、句末都可以。但是放在句首较为普遍。如：
Mother was ill, therefore, she stayed at home yesterday.
= Mother was ill, she therefore, stayed at home yesterday.
= Mother was ill, she stayed at home yesterday, therefore.
3)两个并列连词不可以连用。如：
He tried hard． and but he failed to get the job.此句中的 but应改为 yet。因为 and和 but都是连词。
5．从属连词是用来引导从句，如宾语从句、状语从句、定语从句等。从属连词有 that， if, unless, whether, who, whose, what, which, where, than, when, while, as, since, though, although, because, before, after, until, as soon as, now that, so... that, so that, as... as, (not) as/ so… as如：
If it snows tomorrow， we won't go on a picnic.（ If引导条件状语从句）
Could you tell me whose PC it is? （ whose引导宾语从句）
The man who is talking to my class teacher is my father.（ who引导定语从句）
