Modals of necessity: have to, need to, must

I would like to learn computer programming.

I have to learn computer programming​.

​How are these sentences different in meaning?

I would like to learn computer programming.

​(talks about a wish)

I have to learn computer programming​.

​(talks about a necessity)

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have to: ter que

need to: precisar (de)

​must: deve

-> ​Use them to say something is necessary.

After have to / need to / ​must use the base form of the verb.

​She has to attend the meeting tomorrow.

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don't/didn't have to: não ter que

don't/didn't need to: não precisar (de)

​must not / mustn't: não deve

-> ​Use them to say something is not necessary.

Especially in American English, must is not used often in everyday speech. In most cases, have to is used:

I have to be on time for class today.

Must, when used at all, is used in formal written rules, or only for strong emphasis:

Students must pay their fees by June 25.

​There's no change in third person when must is used.

​Pay attention on the sentences when you use the modals, especially when you notice if it's in the present or past.

​

​She didn't have to do the dishes yesterday.

(the sentence is in the past because 'yesterday' appears there)