（一）連詞概述
連詞是連線單詞、短語或句子的一種虛詞。在句中不單獨作句子成分。歷年會考中常考並列連詞and，but，neither… nor；從屬連詞now that，though，when。所以瞭解狀語從句和賓語從句的真正意義有助於正確使用從屬連詞。
（二）基礎知識梳理
1．並列連詞用來連線彼此並列的詞、短語或句子。並列連詞有and，or，but，so，for，nor等。
2．關聯連詞有both…and，either… or，neither…nor，not only…but also，as well as，as much as等。
3．連線性副詞有however，therefore，besides，yet，anyway，still，all the same等。
4．並列連詞和連線性副詞存在以下的區別：
1)連線兩個獨立的'分句時，並列連詞的位置只能放在它所引導的分句的句首，前面通常有逗號。如：
I must work hard, for I still have a long way to go.
They all went, but I didn't go.
2)連線性副詞的位置比較靈活，句中、句首、句末都可以。但是放在句首較為普遍。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)兩個並列連詞不可以連用。如：
He tried hard．and but he failed to get the job.此句中的but應改為yet。因為and和but都是連詞。
5．從屬連詞是用來引導從句，如賓語從句、狀語從句、定語從句等。從屬連詞有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, as... as,(not) as/so…as 如：
If it snows tomorrow，we won't go on a picnic.（If引導條件狀語從句）
Could you tell me whose PC it is? （whose引導賓語從句）
The man who is talking to my class teacher is my father.（who引導定語從句）
