连词重点用法
1.表示并列关系的连词有：and，both…and…，not only… but also…和neither…nor…
1)and的特别用法：
祈使句后连接and，有条件句作用，此时and=if you…，you'll…
Go straight on, and you'll see the library.==If you go straight on, you will see the library.
2)both…and…既…也…，(两者)都…
A.both…and…谓语动词一般用复数。
Both Jim and Kate are from England.
B.both…and…否定句表示部分否定。
Both my father and my mother aren't doctors.我的父母只有一个人是医生。
3)neither…nor…：既不…也不…
neither…nor…连接两个并列主语时，谓语动词靠近哪个主语就与哪个主语保持“人称”和“数”的一致，即采取就近原则。Neither I nor he has seen the play before.
4)not only…but also…：不但…而且…
not only…but also…连接两个主语后的谓语动词也遵循就近原则。
Not only the mother but also the children are ill.
2.表示转折关系的连词有：but，however，yet，still，while等。
Mary was a nice girl, but she had one shortcoming.
Tom got up early, yet he failed to catch the train.
He was very tired, still he kept on walking.
Your composition is fairly good, however, there is still some room for improvement.
Jane is hard working, while her sister is quite lazy.
3.表示选择关系的并列连词有：or，either…or…，whether… or…等。
1)or：或、否则
A：基本用法
or 表示“或” 的意思，使用于两者之中选择一个的时候。
----Is your friend English or American? ----American.
He doesn't like dumplings or noodles.
B：特别用法
祁使句后连接or，表“如果…，否则…”，有转折的意思，此时or =if you don't …，you’ll …
Hurry up, or you'll be late.=If you don’t hurry up, you'll be late.
2)either…or…：或者…或者…;不是…就是…;要么…要么…
A. either…or…连接两个并列主语时，谓语动词靠近哪个主语就与哪个主语保持“人称”和“数”的一致，即就近原则。
Either you or I am right. Does either she or they like English?
B. 由either…or…引导的否定句是完全否定。
She isn't either a student or a teacher.
3)whether…or…不管…还是…
She is always cheerful, whether at home or at school.
4.表示因果关系的并列连词有：for(因为)，so(所以)。
He is not at school today, for he has a bad cold.
It was late, so I went home.
