2015年英语四级考试语法知识61
发布时间：2013/9/7 23:20:27 来源：城市网学院 编辑：admin
形式变化
1)没有人称和数的变化，第三人称单数的现在时也无变化。如：
I can We can
You can You can
He
They can
She can
It
2)有些情态动词有过去式，有少数过去式和它的原形相同。
a)有过去式的情态动词有：
may -- would
can ―― could
may―― night
shall -- should
have to -- had to
b)过去式不变的情态动词有：
must - must (或had to)
ought to - ought to
need---need
dare - dare(亦可用dared)
3)大多数情态动词后面可用动词的进行式、完成式和被动形式，如：can(may，must)be doing，can(may，must) have done，can(may，must)be done等。
否定式
情态动词和助动词一样，后面可直接跟否定词not。现将情态动词的否定式及其否定式的简略式(简略式用于口语中)列举如下：
shall not--shan't [FB:nt]
will not---won't [wEunt]
can not-can't [kB:nt]
must not-mustn't [5mQsnt]
should not-- shouldn't
would not-- wouldn't
could not-- couldn't
dare not- daren't [dZEnt]
need not-- needn't
在疑问句中的用法
情态动词在疑问句中的用法和助动词相同。如：
May I ask you a question? 我可以问你一个问题吗?
Can you let me use your dictionary for a minute? 你能把字典借我用一会儿吗?
Would you like to visit the heavy machinery plant? 你想参观重型机器厂吗?
注意have to在疑问句中的位置。如：
Do you have to go out today? 你今天一定得出去吗?
Does he have to finish the work tomorrow? 他明天非做完这项工作不可吗?
[英语语法手册]情态动词－－can, could
