could retroact
Verbo regular: retroact - retroacted- retroacted

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could retroact
you could retroact
he could retroact
we could retroact
you could retroact
they could retroact 	I could be retroacting
you could be retroacting
he could be retroacting
we could be retroacting
you could be retroacting
they could be retroacting	I could have retroacted
you could have retroacted
he could have retroacted
we could have retroacted
you could have retroacted
they could have retroacted	I could have been retroacting
you could have been retroacting
he could have been retroacting
we could have been retroacting
you could have been retroacting
they could have been retroacting	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not retroact
you could not retroact
he could not retroact
we could not retroact
you could not retroact
they could not retroact 	I could not be retroacting
you could not be retroacting
he could not be retroacting
we could not be retroacting
you could not be retroacting
they could not be retroacting	I could not have retroacted
you could not have retroacted
he could not have retroacted
we could not have retroacted
you could not have retroacted
they could not have retroacted	I could not have been retroacting
you could not have been retroacting
he could not have been retroacting
we could not have been retroacting
you could not have been retroacting
they could not have been retroacting	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I retroact?
could you retroact?
could he retroact?
could we retroact?
could you retroact?
could they retroact? 	could I be retroacting?
could you be retroacting?
could he be retroacting?
could we be retroacting?
could you be retroacting?
could they be retroacting? 	could I have retroacted?
could you have retroacted?
could he have retroacted?
could we have retroacted?
could you have retroacted?
could they have retroacted? 	could I have been retroacting?
could you have been retroacting?
could he have been retroacting?
could we have been retroacting?
could you have been retroacting?
could they have been retroacting? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not retroact?
could you not retroact?
could he not retroact?
could we not retroact?
could you not retroact?
could they not retroact? 	could I not be retroacting?
could you not be retroacting?
could he not be retroacting?
could we not be retroacting?
could you not be retroacting?
could they not be retroacting? 	could I not have retroacted?
could you not have retroacted?
could he not have retroacted?
could we not have retroacted?
could you not have retroacted?
could they not have retroacted? 	could I not have been retroacting?
could you not have been retroacting?
could he not have been retroacting?
could we not have been retroacting?
could you not have been retroacting?
could they not have been retroacting?