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 could not stopper
you could not stopper
he could not stopper
we could not stopper
you could not stopper
they could not stopper 	I could not be stoppering
you could not be stoppering
he could not be stoppering
we could not be stoppering
you could not be stoppering
they could not be stoppering	I could not have stoppered
you could not have stoppered
he could not have stoppered
we could not have stoppered
you could not have stoppered
they could not have stoppered	I could not have been stoppering
you could not have been stoppering
he could not have been stoppering
we could not have been stoppering
you could not have been stoppering
they could not 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 	
could I not stopper?
could you not stopper?
could he not stopper?
could we not stopper?
could you not stopper?
could they not stopper? 	could I not be stoppering?
could you not be stoppering?
could he not be stoppering?
could we not be stoppering?
could you not be stoppering?
could they not be stoppering? 	could I not have stoppered?
could you not have stoppered?
could he not have stoppered?
could we not have stoppered?
could you not have stoppered?
could they not have stoppered? 	could I not have been stoppering?
could you not have been stoppering?
could he not have been stoppering?
could we not have been stoppering?
could you not have been stoppering?
could they not have been stoppering?