could stopper
Regular verb: stopper - stoppered- stoppered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could stopper
you could stopper
he could stopper
we could stopper
you could stopper
they could stopper 	I could be stoppering
you could be stoppering
he could be stoppering
we could be stoppering
you could be stoppering
they could be stoppering	I could have stoppered
you could have stoppered
he could have stoppered
we could have stoppered
you could have stoppered
they could have stoppered	I could have been stoppering
you could have been stoppering
he could have been stoppering
we could have been stoppering
you could have been stoppering
they could have been stoppering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't stopper
you couldn't stopper
he couldn't stopper
we couldn't stopper
you couldn't stopper
they couldn't stopper 	I couldn't be stoppering
you couldn't be stoppering
he couldn't be stoppering
we couldn't be stoppering
you couldn't be stoppering
they couldn't be stoppering	I couldn't have stoppered
you couldn't have stoppered
he couldn't have stoppered
we couldn't have stoppered
you couldn't have stoppered
they couldn't have stoppered	I couldn't have been stoppering
you couldn't have been stoppering
he couldn't have been stoppering
we couldn't have been stoppering
you couldn't have been stoppering
they couldn't have been stoppering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I stopper?
could you stopper?
could he stopper?
could we stopper?
could you stopper?
could they stopper? 	could I be stoppering?
could you be stoppering?
could he be stoppering?
could we be stoppering?
could you be stoppering?
could they be stoppering? 	could I have stoppered?
could you have stoppered?
could he have stoppered?
could we have stoppered?
could you have stoppered?
could they have stoppered? 	could I have been stoppering?
could you have been stoppering?
could he have been stoppering?
could we have been stoppering?
could you have been stoppering?
could they have been stoppering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I stopper?
couldn't you stopper?
couldn't he stopper?
couldn't we stopper?
couldn't you stopper?
couldn't they stopper? 	couldn't I be stoppering?
couldn't you be stoppering?
couldn't he be stoppering?
couldn't we be stoppering?
couldn't you be stoppering?
couldn't they be stoppering? 	couldn't I have stoppered?
couldn't you have stoppered?
couldn't he have stoppered?
couldn't we have stoppered?
couldn't you have stoppered?
couldn't they have stoppered? 	couldn't I have been stoppering?
couldn't you have been stoppering?
couldn't he have been stoppering?
couldn't we have been stoppering?
couldn't you have been stoppering?
couldn't they have been stoppering?