Modal verbs

Have to/don't have toExpressing an external obligation, a necessity in the past or recommendationsExample: I have to do my homework/ You don't have to go if you don't want to.

Modal

Giving permission or ability in the present or futureExample: I can swim

Can

verbs

Could

Actions you are allowed to do or ability in the pastExample: Could I repeat my exam?

Should/shouldn't:To giving advices or expressing an opinion.Example: You should do the homeworkHe shoudn't eat soo much sweets

Must/mustn'tExpressing obligations or prohibitionsExample: You must clean your room/You mustn't smoke

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Jose Tejera Rodríguez