Modal Verbs in English, How to Use Modals CAN Ability, doubt, astonishment, permission, Polite request MAY Permission, if not prohibition, supposition with doubt MUST Obligation, firm necessity, logical conclusion, probability SHALL intention, supposition WILL Wish, desire, will, confidence, in the future OUGHT TO Moral duty, insistent advice, strict recommendation NEED (un)necessity BE TO Obligation arising out of arrangement or agreement HAVE TO Unwillingness, forced circumtances WOULD Wish (with “to like”), polite request, a habit of the past SHOULD Necessity, advice, blame, recommendation, reproach, regret USED TO Repeated action in the past