could ball
Regular verb: ball - balled- balled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could ball
you could ball
he could ball
we could ball
you could ball
they could ball 	I could be balling
you could be balling
he could be balling
we could be balling
you could be balling
they could be balling	I could have balled
you could have balled
he could have balled
we could have balled
you could have balled
they could have balled	I could have been balling
you could have been balling
he could have been balling
we could have been balling
you could have been balling
they could have been balling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not ball
you could not ball
he could not ball
we could not ball
you could not ball
they could not ball 	I could not be balling
you could not be balling
he could not be balling
we could not be balling
you could not be balling
they could not be balling	I could not have balled
you could not have balled
he could not have balled
we could not have balled
you could not have balled
they could not have balled	I could not have been balling
you could not have been balling
he could not have been balling
we could not have been balling
you could not have been balling
they could not have been balling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I ball?
could you ball?
could he ball?
could we ball?
could you ball?
could they ball? 	could I be balling?
could you be balling?
could he be balling?
could we be balling?
could you be balling?
could they be balling? 	could I have balled?
could you have balled?
could he have balled?
could we have balled?
could you have balled?
could they have balled? 	could I have been balling?
could you have been balling?
could he have been balling?
could we have been balling?
could you have been balling?
could they have been balling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not ball?
could you not ball?
could he not ball?
could we not ball?
could you not ball?
could they not ball? 	could I not be balling?
could you not be balling?
could he not be balling?
could we not be balling?
could you not be balling?
could they not be balling? 	could I not have balled?
could you not have balled?
could he not have balled?
could we not have balled?
could you not have balled?
could they not have balled? 	could I not have been balling?
could you not have been balling?
could he not have been balling?
could we not have been balling?
could you not have been balling?
could they not have been balling?