have to: obligatory, necessary, often describes obligations imposed on us by other people and authorities, don't have to: not obligatory, not necessary, must: rules, regulations, and obligations, often describes obligations that come internally, from ourselves, mustn't: prohibitions, can: to give permission, can't: refuse permission, should, shouldn't, ought to, had ('d) better: to give advice and recommendations, to ask for advice and recommendations,

5.2 Modals sorting

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