must unfasten
Regular verb: unfasten - unfastened- unfastened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must unfasten
you must unfasten
he must unfasten
we must unfasten
you must unfasten
they must unfasten 	I must be unfastening
you must be unfastening
he must be unfastening
we must be unfastening
you must be unfastening
they must be unfastening	I must have unfastened
you must have unfastened
he must have unfastened
we must have unfastened
you must have unfastened
they must have unfastened	I must have been unfastening
you must have been unfastening
he must have been unfastening
we must have been unfastening
you must have been unfastening
they must have been unfastening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't unfasten
you mustn't unfasten
he mustn't unfasten
we mustn't unfasten
you mustn't unfasten
they mustn't unfasten 	I mustn't be unfastening
you mustn't be unfastening
he mustn't be unfastening
we mustn't be unfastening
you mustn't be unfastening
they mustn't be unfastening	I mustn't have unfastened
you mustn't have unfastened
he mustn't have unfastened
we mustn't have unfastened
you mustn't have unfastened
they mustn't have unfastened	I mustn't have been unfastening
you mustn't have been unfastening
he mustn't have been unfastening
we mustn't have been unfastening
you mustn't have been unfastening
they mustn't have been unfastening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I unfasten?
must you unfasten?
must he unfasten?
must we unfasten?
must you unfasten?
must they unfasten? 	must I be unfastening?
must you be unfastening?
must he be unfastening?
must we be unfastening?
must you be unfastening?
must they be unfastening? 	must I have unfastened?
must you have unfastened?
must he have unfastened?
must we have unfastened?
must you have unfastened?
must they have unfastened? 	must I have been unfastening?
must you have been unfastening?
must he have been unfastening?
must we have been unfastening?
must you have been unfastening?
must they have been unfastening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I unfasten?
mustn't you unfasten?
mustn't he unfasten?
mustn't we unfasten?
mustn't you unfasten?
mustn't they unfasten? 	mustn't I be unfastening?
mustn't you be unfastening?
mustn't he be unfastening?
mustn't we be unfastening?
mustn't you be unfastening?
mustn't they be unfastening? 	mustn't I have unfastened?
mustn't you have unfastened?
mustn't he have unfastened?
mustn't we have unfastened?
mustn't you have unfastened?
mustn't they have unfastened? 	mustn't I have been unfastening?
mustn't you have been unfastening?
mustn't he have been unfastening?
mustn't we have been unfastening?
mustn't you have been unfastening?
mustn't they have been unfastening?