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 must not unfasten
you must not unfasten
he must not unfasten
we must not unfasten
you must not unfasten
they must not unfasten 	I must not be unfastening
you must not be unfastening
he must not be unfastening
we must not be unfastening
you must not be unfastening
they must not be unfastening	I must not have unfastened
you must not have unfastened
he must not have unfastened
we must not have unfastened
you must not have unfastened
they must not have unfastened	I must not have been unfastening
you must not have been unfastening
he must not have been unfastening
we must not have been unfastening
you must not have been unfastening
they must not 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 	
must I not unfasten?
must you not unfasten?
must he not unfasten?
must we not unfasten?
must you not unfasten?
must they not unfasten? 	must I not be unfastening?
must you not be unfastening?
must he not be unfastening?
must we not be unfastening?
must you not be unfastening?
must they not be unfastening? 	must I not have unfastened?
must you not have unfastened?
must he not have unfastened?
must we not have unfastened?
must you not have unfastened?
must they not have unfastened? 	must I not have been unfastening?
must you not have been unfastening?
must he not have been unfastening?
must we not have been unfastening?
must you not have been unfastening?
must they not have been unfastening?