# modal verbs（一）

modal的意思是模式的，情态的，形式的。Bootstrap中的模态框就是这个词modal。

• need和dare既可以做情态动词也可以做实义动词，所以容易提到情态动词不太容易想到这两个。
• have (has,had) to , used to是具有情态动词特征的动词。

# 一、modal verb的formulation

• They are always follwed by the 'infinitive without to' 后面加不带to的动词不定式
• They are same for all the pronouns. 所有的代词都用同样的modal verb,没有什么单三之类的。
• They do not need auxiliaries. They take direct negative and question forms.modal verb不需要助动词，它直接加not就是否定形式。比如want“想要”，表达“不想要”我们需要助动词do的否定形式我们会说do not want；但是情态动词can 直接就是can not。
• They never combine with another modal verb.

# 二、can

## 1，Ability or lack of ability in the present or future.

• They can't dance.
• Man can not live without air.

## 2，Giving / not giving permission

• You can use my office.
• You can't smoke here.

## 3，表示惊异，怀疑，不相信的态度（用在否定句，疑问句或惊叹句）

• Can this be true?
• How can you be so careless!
• This cannot be done by him.

## 4，can(could) + have + 过去分词”的疑问或否定形式表示对过去发生的行为怀疑或不肯定

• He cannot have been to that town.
• Can he have got the book?

## 5，cannottoo\enough表示"无论怎样也不过分","越`越好"

• You cannot be too careful to cross the street.
• I can not thank enough for your kindness.我再怎么感谢你的好意也不为过。（我应该好好感谢你。）

# 三、could

## 1，Ability or lack of ability in the past

• I could read without glasses last year.去年我还可以不戴眼镜看书，言外之意就是今年就不可以啦，我老啦之类的.
• I could not sleep last night.

## 2，在疑问句中making a request时候用

• Could you repeat that please?
• Could we have a break please?

could表示请求语气很委婉。用的非常多，记得要多用，记得回答用can.

Could I come to see you tomorrow?

• Yes, you can.
• No, I'm afraid not.

## 3，用在肯定句中Making a suggestion

What do you suggest we have for dinner? We could have fish.

posted @ 2017-09-19 22:21  starof  阅读(3073)  评论(0编辑  收藏  举报