Models
Criticism
(PAST) Should (not) have done(V3)
(PAST) Ought (not) to have done(V3)
Obligation
(PR) Must (must not)
(PR) Have to (don't have to)
(PR) Need to
Needn't
Don't need to
Be supposed to
(PAST) Had to (didn't have to)
(PAST) Need have V3 (nedn't have done(V3))
(PAST) Needed to (didn't need to)
Degrees of certainty
Certainty (90-99%)
(PR) Must, can't, couldn't
(PAST) must, can't, couldn't + have V3
Probability
(PR) Should, ought to
(PAST) should, ought to + have V3
Posibility
(PR) May, could, might
(PAST) may, could, might + have V3
Ability
(PR) Can (for present and future situations)
(PR) Could (for unreal)
(PAST) Could (for past situation(real))
(PAST) Could have V3 (for unreal situation)
Permission
(PR) May (most polite)
(PR) Could (less polite)
(PR) Can (unpolite)
(PAST) Be allowed to
(PAST) Could (for reported)
Advice
(PR) Should
(PR) Ought to
(PR) Had better to do