could unfasten
Regular verb: unfasten - unfastened- unfastened

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not unfasten
you could not unfasten
she could not unfasten
we could not unfasten
you could not unfasten
they could not unfasten 	I could not be unfastening
you could not be unfastening
she could not be unfastening
we could not be unfastening
you could not be unfastening
they could not be unfastening	I could not have unfastened
you could not have unfastened
she could not have unfastened
we could not have unfastened
you could not have unfastened
they could not have unfastened	I could not have been unfastening
you could not have been unfastening
she could not have been unfastening
we could not have been unfastening
you could not have been unfastening
they could not have been unfastening	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not unfasten?
could you not unfasten?
could she not unfasten?
could we not unfasten?
could you not unfasten?
could they not unfasten? 	could I not be unfastening?
could you not be unfastening?
could she not be unfastening?
could we not be unfastening?
could you not be unfastening?
could they not be unfastening? 	could I not have unfastened?
could you not have unfastened?
could she not have unfastened?
could we not have unfastened?
could you not have unfastened?
could they not have unfastened? 	could I not have been unfastening?
could you not have been unfastening?
could she not have been unfastening?
could we not have been unfastening?
could you not have been unfastening?
could they not have been unfastening?