English verb conjugation
MUST SIGH

Regular verb: sigh - sighed - sighed

Affirmation

Simple form	V-ing form
I must sigh you must sigh he must sigh we must sigh you must sigh they must sigh	I must be sighing you must be sighing he must be sighing we must be sighing you must be sighing they must be sighing
Perfect	V-ing perfect
I must have sighed you must have sighed he must have sighed we must have sighed you must have sighed they must have sighed	I must have been sighing you must have been sighing he must have been sighing we must have been sighing you must have been sighing they must have been sighing

Negation

Simple form	V-ing form
I must not sigh you must not sigh he must not sigh we must not sigh you must not sigh they must not sigh	I must not be sighing you must not be sighing he must not be sighing we must not be sighing you must not be sighing they must not be sighing
Perfect	V-ing perfect
I must not have sighed you must not have sighed he must not have sighed we must not have sighed you must not have sighed they must not have sighed	I must not have been sighing you must not have been sighing he must not have been sighing we must not have been sighing you must not have been sighing they must not have been sighing

Interrogative form

Simple form	V-ing form
must I sigh? must you sigh? must he sigh? must we sigh? must you sigh? must they sigh?	must I be sighing? must you be sighing? must he be sighing? must we be sighing? must you be sighing? must they be sighing?
Perfect	V-ing perfect
must I have sighed? must you have sighed? must he have sighed? must we have sighed? must you have sighed? must they have sighed?	must I have been sighing? must you have been sighing? must he have been sighing? must we have been sighing? must you have been sighing? must they have been sighing?

Interro-negative form

Simple form	V-ing form
must I not sigh? must you not sigh? must he not sigh? must we not sigh? must you not sigh? must they not sigh?	must I not be sighing? must you not be sighing? must he not be sighing? must we not be sighing? must you not be sighing? must they not be sighing?
Perfect	V-ing perfect
must I not have sighed? must you not have sighed? must he not have sighed? must we not have sighed? must you not have sighed? must they not have sighed?	must I not have been sighing? must you not have been sighing? must he not have been sighing? must we not have been sighing? must you not have been sighing? must they not have been sighing?