could unlock
Regular verb: unlock - unlocked- unlocked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could unlock
you could unlock
she could unlock
we could unlock
you could unlock
they could unlock 	I could be unlocking
you could be unlocking
she could be unlocking
we could be unlocking
you could be unlocking
they could be unlocking	I could have unlocked
you could have unlocked
she could have unlocked
we could have unlocked
you could have unlocked
they could have unlocked	I could have been unlocking
you could have been unlocking
she could have been unlocking
we could have been unlocking
you could have been unlocking
they could have been unlocking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't unlock
you couldn't unlock
she couldn't unlock
we couldn't unlock
you couldn't unlock
they couldn't unlock 	I couldn't be unlocking
you couldn't be unlocking
she couldn't be unlocking
we couldn't be unlocking
you couldn't be unlocking
they couldn't be unlocking	I couldn't have unlocked
you couldn't have unlocked
she couldn't have unlocked
we couldn't have unlocked
you couldn't have unlocked
they couldn't have unlocked	I couldn't have been unlocking
you couldn't have been unlocking
she couldn't have been unlocking
we couldn't have been unlocking
you couldn't have been unlocking
they couldn't have been unlocking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I unlock?
could you unlock?
could she unlock?
could we unlock?
could you unlock?
could they unlock? 	could I be unlocking?
could you be unlocking?
could she be unlocking?
could we be unlocking?
could you be unlocking?
could they be unlocking? 	could I have unlocked?
could you have unlocked?
could she have unlocked?
could we have unlocked?
could you have unlocked?
could they have unlocked? 	could I have been unlocking?
could you have been unlocking?
could she have been unlocking?
could we have been unlocking?
could you have been unlocking?
could they have been unlocking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I unlock?
couldn't you unlock?
couldn't she unlock?
couldn't we unlock?
couldn't you unlock?
couldn't they unlock? 	couldn't I be unlocking?
couldn't you be unlocking?
couldn't she be unlocking?
couldn't we be unlocking?
couldn't you be unlocking?
couldn't they be unlocking? 	couldn't I have unlocked?
couldn't you have unlocked?
couldn't she have unlocked?
couldn't we have unlocked?
couldn't you have unlocked?
couldn't they have unlocked? 	couldn't I have been unlocking?
couldn't you have been unlocking?
couldn't she have been unlocking?
couldn't we have been unlocking?
couldn't you have been unlocking?
couldn't they have been unlocking?