could corkscrew
Regular verb: corkscrew - corkscrewed- corkscrewed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could corkscrew
you could corkscrew
he could corkscrew
we could corkscrew
you could corkscrew
they could corkscrew 	I could be corkscrewing
you could be corkscrewing
he could be corkscrewing
we could be corkscrewing
you could be corkscrewing
they could be corkscrewing	I could have corkscrewed
you could have corkscrewed
he could have corkscrewed
we could have corkscrewed
you could have corkscrewed
they could have corkscrewed	I could have been corkscrewing
you could have been corkscrewing
he could have been corkscrewing
we could have been corkscrewing
you could have been corkscrewing
they could have been corkscrewing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't corkscrew
you couldn't corkscrew
he couldn't corkscrew
we couldn't corkscrew
you couldn't corkscrew
they couldn't corkscrew 	I couldn't be corkscrewing
you couldn't be corkscrewing
he couldn't be corkscrewing
we couldn't be corkscrewing
you couldn't be corkscrewing
they couldn't be corkscrewing	I couldn't have corkscrewed
you couldn't have corkscrewed
he couldn't have corkscrewed
we couldn't have corkscrewed
you couldn't have corkscrewed
they couldn't have corkscrewed	I couldn't have been corkscrewing
you couldn't have been corkscrewing
he couldn't have been corkscrewing
we couldn't have been corkscrewing
you couldn't have been corkscrewing
they couldn't have been corkscrewing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I corkscrew?
could you corkscrew?
could he corkscrew?
could we corkscrew?
could you corkscrew?
could they corkscrew? 	could I be corkscrewing?
could you be corkscrewing?
could he be corkscrewing?
could we be corkscrewing?
could you be corkscrewing?
could they be corkscrewing? 	could I have corkscrewed?
could you have corkscrewed?
could he have corkscrewed?
could we have corkscrewed?
could you have corkscrewed?
could they have corkscrewed? 	could I have been corkscrewing?
could you have been corkscrewing?
could he have been corkscrewing?
could we have been corkscrewing?
could you have been corkscrewing?
could they have been corkscrewing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I corkscrew?
couldn't you corkscrew?
couldn't he corkscrew?
couldn't we corkscrew?
couldn't you corkscrew?
couldn't they corkscrew? 	couldn't I be corkscrewing?
couldn't you be corkscrewing?
couldn't he be corkscrewing?
couldn't we be corkscrewing?
couldn't you be corkscrewing?
couldn't they be corkscrewing? 	couldn't I have corkscrewed?
couldn't you have corkscrewed?
couldn't he have corkscrewed?
couldn't we have corkscrewed?
couldn't you have corkscrewed?
couldn't they have corkscrewed? 	couldn't I have been corkscrewing?
couldn't you have been corkscrewing?
couldn't he have been corkscrewing?
couldn't we have been corkscrewing?
couldn't you have been corkscrewing?
couldn't they have been corkscrewing?