could canker
Regular verb: canker - cankered- cankered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could canker
you could canker
he could canker
we could canker
you could canker
they could canker 	I could be cankering
you could be cankering
he could be cankering
we could be cankering
you could be cankering
they could be cankering	I could have cankered
you could have cankered
he could have cankered
we could have cankered
you could have cankered
they could have cankered	I could have been cankering
you could have been cankering
he could have been cankering
we could have been cankering
you could have been cankering
they could have been cankering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't canker
you couldn't canker
he couldn't canker
we couldn't canker
you couldn't canker
they couldn't canker 	I couldn't be cankering
you couldn't be cankering
he couldn't be cankering
we couldn't be cankering
you couldn't be cankering
they couldn't be cankering	I couldn't have cankered
you couldn't have cankered
he couldn't have cankered
we couldn't have cankered
you couldn't have cankered
they couldn't have cankered	I couldn't have been cankering
you couldn't have been cankering
he couldn't have been cankering
we couldn't have been cankering
you couldn't have been cankering
they couldn't have been cankering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I canker?
could you canker?
could he canker?
could we canker?
could you canker?
could they canker? 	could I be cankering?
could you be cankering?
could he be cankering?
could we be cankering?
could you be cankering?
could they be cankering? 	could I have cankered?
could you have cankered?
could he have cankered?
could we have cankered?
could you have cankered?
could they have cankered? 	could I have been cankering?
could you have been cankering?
could he have been cankering?
could we have been cankering?
could you have been cankering?
could they have been cankering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I canker?
couldn't you canker?
couldn't he canker?
couldn't we canker?
couldn't you canker?
couldn't they canker? 	couldn't I be cankering?
couldn't you be cankering?
couldn't he be cankering?
couldn't we be cankering?
couldn't you be cankering?
couldn't they be cankering? 	couldn't I have cankered?
couldn't you have cankered?
couldn't he have cankered?
couldn't we have cankered?
couldn't you have cankered?
couldn't they have cankered? 	couldn't I have been cankering?
couldn't you have been cankering?
couldn't he have been cankering?
couldn't we have been cankering?
couldn't you have been cankering?
couldn't they have been cankering?