could ball
Regular verb: ball - balled- balled

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