English verb conjugation
MUST SING

Irregular verb: sing - sang - sung

Affirmation

Simple form	V-ing form
I must sing you must sing he must sing we must sing you must sing they must sing	I must be singing you must be singing he must be singing we must be singing you must be singing they must be singing
Perfect	V-ing perfect
I must have sung you must have sung he must have sung we must have sung you must have sung they must have sung	I must have been singing you must have been singing he must have been singing we must have been singing you must have been singing they must have been singing

Negation

Simple form	V-ing form
I mustn't sing you mustn't sing he mustn't sing we mustn't sing you mustn't sing they mustn't sing	I mustn't be singing you mustn't be singing he mustn't be singing we mustn't be singing you mustn't be singing they mustn't be singing
Perfect	V-ing perfect
I mustn't have sung you mustn't have sung he mustn't have sung we mustn't have sung you mustn't have sung they mustn't have sung	I mustn't have been singing you mustn't have been singing he mustn't have been singing we mustn't have been singing you mustn't have been singing they mustn't have been singing

Interrogative form

Simple form	V-ing form
must I sing? must you sing? must he sing? must we sing? must you sing? must they sing?	must I be singing? must you be singing? must he be singing? must we be singing? must you be singing? must they be singing?
Perfect	V-ing perfect
must I have sung? must you have sung? must he have sung? must we have sung? must you have sung? must they have sung?	must I have been singing? must you have been singing? must he have been singing? must we have been singing? must you have been singing? must they have been singing?

Interro-negative form

Simple form	V-ing form
mustn't I sing? mustn't you sing? mustn't he sing? mustn't we sing? mustn't you sing? mustn't they sing?	mustn't I be singing? mustn't you be singing? mustn't he be singing? mustn't we be singing? mustn't you be singing? mustn't they be singing?
Perfect	V-ing perfect
mustn't I have sung? mustn't you have sung? mustn't he have sung? mustn't we have sung? mustn't you have sung? mustn't they have sung?	mustn't I have been singing? mustn't you have been singing? mustn't he have been singing? mustn't we have been singing? mustn't you have been singing? mustn't they have been singing?