Modals: Permission – Can, Could, May
Modals: Advice – Should & Ought To
Modals: Obligation & Prohibition – Must, Have To
Modals: Ability – Can, Could, Be able to
Modals: Possibility – May, Could, Might
Modals: Certainty – Must, Can’t, Couldn’t
Modals: Deduction & Speculation in the past
Modals: Will, Shall, Would