English verb conjugation
MUST SING

Irregular verb: sing - sang - sung

Affirmation

Simple form	V-ing form
I must sing you must sing she must sing we must sing you must sing they must sing	I must be singing you must be singing she 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 she 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 she 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 must not sing you must not sing she must not sing we must not sing you must not sing they must not sing	I must not be singing you must not be singing she must not be singing we must not be singing you must not be singing they must not be singing
Perfect	V-ing perfect
I must not have sung you must not have sung she must not have sung we must not have sung you must not have sung they must not have sung	I must not have been singing you must not have been singing she must not have been singing we must not have been singing you must not have been singing they must not have been singing

Interrogative form

Simple form	V-ing form
must I sing? must you sing? must she sing? must we sing? must you sing? must they sing?	must I be singing? must you be singing? must she 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 she 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 she 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
must I not sing? must you not sing? must she not sing? must we not sing? must you not sing? must they not sing?	must I not be singing? must you not be singing? must she not be singing? must we not be singing? must you not be singing? must they not be singing?
Perfect	V-ing perfect
must I not have sung? must you not have sung? must she not have sung? must we not have sung? must you not have sung? must they not have sung?	must I not have been singing? must you not have been singing? must she not have been singing? must we not have been singing? must you not have been singing? must they not have been singing?