must retroact
Verbo regular: retroact - retroacted- retroacted

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

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

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

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