might/should have known

: past tense of may

used to express permission, liberty, probability, or possibility in the past

used to say that something is possible

: the power, authority, or resources wielded (as by an individual or group)

: bodily strength

: the power, energy, or intensity of which one is capable

: past tense of shall

used in auxiliary function to express condition

used in auxiliary function to express obligation, propriety, or expediency

: generally recognized