摘要：如：Speak clearly so that they may/might understand you.（说清楚点，以便他们能理解你。）

1.may和might的用法

-表允might更委婉。

You may take whatever you like.

He told me that I might smoke in the room.

-表可能，语气不肯定，

I'm afraid they may not agree with him。

- 用于目的状语从句：在表示目的的状语从句中，

如：Speak clearly so that they may/might understand you.（说清楚点，以便他们能理解你。）

- 用于让步状语从句：可用于让步状语从句中，意为“尽管，即使”。如：May/Might he be rich or poor, I will love him all the same.（无论他是富有还是贫穷，我都会一样爱他。）

2.must的用法

-表必须(主观意志)，

we must do everything we can to help him。

-Must we hand in our exercise books now?

-No,you needn't./you don't have to。

-表示揣测，意为，想必，准是只用于肯定句。

-He must be ill, he looks so pale.

-She must have a lot of money,for she have an expensive car.

-表示责备，抱怨的感情色彩，意为偏偏，偏要

1).-How old are you ?

-If you must know ,I'm twice my son's age。

2)- If you must go, at least wait until the rain stops.（如果你非要走，至少等到雨停吧。）

- must+be+形容词最高级+名词：表示“一定是最……的……之一”。如：This must be one of the most beautiful cities in the world.（这一定是世界上最美丽的城市之一。）

3. have to的用法

-have to的含义与must是很接近的，只是have to比较强调客观需要，must着重说明主观看法。

-I must clean the room，(主观想法)

-I have to clean the room，(客观需要)，

-mustn't表禁止，而have to的否定式意为不必。

-Smoking mustn't be allowed in the office.

-must we hand in our exercise today，

-No,you don't have to。

- have got to：可用来代替have to，意思相同，常用于口语中。如：I have got to finish my work before I go to bed.（我必须在睡觉前完成我的工作。）

- have to do with：意为“与……有关”。如：What he said has to do with the problem we are discussing.（他说的与我们正在讨论的问题有关）。

真题、模拟题

- 2024年新高考二卷：学校这次数学测试没有几个同学及格是真的吗？那它一定是很难了。从few of the students passed the math quiz this time这句话中能推断出这个考试是肯定很难，要选的答案是对过去事实的肯定推测，要用的结构是must have been。

- 2024年情态动词模拟题：You____let the excellent opportunity slip through your fingers, or you will regret it later. 选项：A. may not；B. wouldn't；C. needn't；D. mustn't。答案：D。根据“or you will regret it later”可知，此处表示“千万不能”让机会溜走，语气最强，用mustn't。

来源：Xin神英语