could ace
Regular verb: ace - aced- aced

Affirmation 	
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I could ace
you could ace
he could ace
we could ace
you could ace
they could ace 	I could be acing
you could be acing
he could be acing
we could be acing
you could be acing
they could be acing	I could have aced
you could have aced
he could have aced
we could have aced
you could have aced
they could have aced	I could have been acing
you could have been acing
he could have been acing
we could have been acing
you could have been acing
they could have been acing	

Negation 	
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I couldn't ace
you couldn't ace
he couldn't ace
we couldn't ace
you couldn't ace
they couldn't ace 	I couldn't be acing
you couldn't be acing
he couldn't be acing
we couldn't be acing
you couldn't be acing
they couldn't be acing	I couldn't have aced
you couldn't have aced
he couldn't have aced
we couldn't have aced
you couldn't have aced
they couldn't have aced	I couldn't have been acing
you couldn't have been acing
he couldn't have been acing
we couldn't have been acing
you couldn't have been acing
they couldn't have been acing	

Interrogative form 	
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could I ace?
could you ace?
could he ace?
could we ace?
could you ace?
could they ace? 	could I be acing?
could you be acing?
could he be acing?
could we be acing?
could you be acing?
could they be acing? 	could I have aced?
could you have aced?
could he have aced?
could we have aced?
could you have aced?
could they have aced? 	could I have been acing?
could you have been acing?
could he have been acing?
could we have been acing?
could you have been acing?
could they have been acing? 	

Interro-negative form 	
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couldn't I ace?
couldn't you ace?
couldn't he ace?
couldn't we ace?
couldn't you ace?
couldn't they ace? 	couldn't I be acing?
couldn't you be acing?
couldn't he be acing?
couldn't we be acing?
couldn't you be acing?
couldn't they be acing? 	couldn't I have aced?
couldn't you have aced?
couldn't he have aced?
couldn't we have aced?
couldn't you have aced?
couldn't they have aced? 	couldn't I have been acing?
couldn't you have been acing?
couldn't he have been acing?
couldn't we have been acing?
couldn't you have been acing?
couldn't they have been acing?