must sing
Irregular verb: sing - sang- sung

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