could screw
Regular verb: screw - screwed- screwed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could screw
you could screw
she could screw
we could screw
you could screw
they could screw 	I could be screwing
you could be screwing
she could be screwing
we could be screwing
you could be screwing
they could be screwing	I could have screwed
you could have screwed
she could have screwed
we could have screwed
you could have screwed
they could have screwed	I could have been screwing
you could have been screwing
she could have been screwing
we could have been screwing
you could have been screwing
they could have been screwing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not screw
you could not screw
she could not screw
we could not screw
you could not screw
they could not screw 	I could not be screwing
you could not be screwing
she could not be screwing
we could not be screwing
you could not be screwing
they could not be screwing	I could not have screwed
you could not have screwed
she could not have screwed
we could not have screwed
you could not have screwed
they could not have screwed	I could not have been screwing
you could not have been screwing
she could not have been screwing
we could not have been screwing
you could not have been screwing
they could not have been screwing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I screw?
could you screw?
could she screw?
could we screw?
could you screw?
could they screw? 	could I be screwing?
could you be screwing?
could she be screwing?
could we be screwing?
could you be screwing?
could they be screwing? 	could I have screwed?
could you have screwed?
could she have screwed?
could we have screwed?
could you have screwed?
could they have screwed? 	could I have been screwing?
could you have been screwing?
could she have been screwing?
could we have been screwing?
could you have been screwing?
could they have been screwing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not screw?
could you not screw?
could she not screw?
could we not screw?
could you not screw?
could they not screw? 	could I not be screwing?
could you not be screwing?
could she not be screwing?
could we not be screwing?
could you not be screwing?
could they not be screwing? 	could I not have screwed?
could you not have screwed?
could she not have screwed?
could we not have screwed?
could you not have screwed?
could they not have screwed? 	could I not have been screwing?
could you not have been screwing?
could she not have been screwing?
could we not have been screwing?
could you not have been screwing?
could they not have been screwing?