Modal verbs features: Modal verbs have more than one meaning: I can swim ability

I’d like (= I would like) is a polite way of saying what you want, or what you want to do:
I’d like some information about hotels, please.
I’d like to try on this jacket, please.

UNIT 12. OBLIGATION

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  In positive must expresses strong obligation and it’s the speaker’s opinion:
  

I must help her, it’s very difficult for her.

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  In positive have to expresses strong obligation, but it isn’t the speaker’s opinion. It’s based on rules, laws, authority and situations:
  

At school we have to wear uniforms.

Instead of have to we can use have got to:

We’ve got to turn off our mobiles at the lesson.

Have to expresses general repeated obligation but have got to expresses an obligation on one particular occasion:
I always have to tell my parents where I’m going.
I’ve got to get up early tomorrow to catch a train.

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  In negative mustn’t means it’s important not to do something:
  

You mustn’t tell her this, otherwise she’ll cry.

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  In negative don’t have to means it is not important to do something. You may do or not do, it’s up to you:
  

You don’t have to read this book. (you can read if you like but it doesn’t matter if you don’t read)

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  In question forms it’s better to use only have to:
  

Do I have to tell you who I’m meeting with.

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  Must has only the present form. In other forms have to is used instead must:
  

You will have to pay if you break his computer down

UNIT 13. NEED

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  Need to means it’s necessary to do something:
  

You need to hurry if you don’t want to be late.

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