Modal Verbs in English

Can, may, must, shall, will, ought to, need, be to, have to, would, should, used to;

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