The document summarizes the different uses of modal verbs in English including:
- Ability, request, possibility, inability expressed by can, could, may/might
- Obligation and necessity expressed by must, have to, need to, shouldn't
- Lack of obligation expressed by needn't, don't have to
- Prohibition expressed by can't, mustn't
- Suggestion and offers expressed by could, would, shall
- Certainty, advice, opinion expressed by must, should/ought to
- Modal perfects express logical conclusions or suppositions about past events.