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.
5.引导时间状语从句的从属连词有:before, after, when, while, as, till, until, since, as soon as等。
After they had planted their crops, they took a rest.
We have learned six lessons since he began to teach us.
As soon as he gets to Beijing, he’ll call me.
1) when, while, as 都表示“当……时”,when从句谓语动词既可以是瞬间动词也可以是延续性动词,可用于主从句动作同时发生或从句动作先于主句动作发生。while从句谓语动词只能是延续性动词,侧重主从句动作同时发生。as引导一个持续性动作,多用于主从句动作同时发生,强调“一边……一边”。
When I came in, my father was cooking.
I came in when/while my father was cooking.
He sang as he walked.
2)until用法:当主句谓语动词是延续性动词时,主从句都用肯定式,译为“直到……为止”;当主句谓语动词是瞬间动词时,主句用否定式,从句用肯定式,即not…..until, 译为“直到……才”。
Mr. Green waited until his children came back.(格林先生一直等到他的孩子们回来)
Mr. Green didn’t go to bed until his children came back. (格林先生直到他的孩子们回来才睡觉)
6. 引导条件状语从句的从属连词有:if(如果), unless(除非,如果……不)等。
If you don’t go soon, you’ll be late.=Unless you go soon, you’ll be late.