must countervail
Verbe régulier : countervail - countervailed- countervailed

Affirmation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I must countervail
you must countervail
he must countervail
we must countervail
you must countervail
they must countervail 	I must be countervailing
you must be countervailing
he must be countervailing
we must be countervailing
you must be countervailing
they must be countervailing	I must have countervailed
you must have countervailed
he must have countervailed
we must have countervailed
you must have countervailed
they must have countervailed	I must have been countervailing
you must have been countervailing
he must have been countervailing
we must have been countervailing
you must have been countervailing
they must have been countervailing	

Négation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I mustn't countervail
you mustn't countervail
he mustn't countervail
we mustn't countervail
you mustn't countervail
they mustn't countervail 	I mustn't be countervailing
you mustn't be countervailing
he mustn't be countervailing
we mustn't be countervailing
you mustn't be countervailing
they mustn't be countervailing	I mustn't have countervailed
you mustn't have countervailed
he mustn't have countervailed
we mustn't have countervailed
you mustn't have countervailed
they mustn't have countervailed	I mustn't have been countervailing
you mustn't have been countervailing
he mustn't have been countervailing
we mustn't have been countervailing
you mustn't have been countervailing
they mustn't have been countervailing	

Forme interrogative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
must I countervail?
must you countervail?
must he countervail?
must we countervail?
must you countervail?
must they countervail? 	must I be countervailing?
must you be countervailing?
must he be countervailing?
must we be countervailing?
must you be countervailing?
must they be countervailing? 	must I have countervailed?
must you have countervailed?
must he have countervailed?
must we have countervailed?
must you have countervailed?
must they have countervailed? 	must I have been countervailing?
must you have been countervailing?
must he have been countervailing?
must we have been countervailing?
must you have been countervailing?
must they have been countervailing? 	

Forme interro-négative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
mustn't I countervail?
mustn't you countervail?
mustn't he countervail?
mustn't we countervail?
mustn't you countervail?
mustn't they countervail? 	mustn't I be countervailing?
mustn't you be countervailing?
mustn't he be countervailing?
mustn't we be countervailing?
mustn't you be countervailing?
mustn't they be countervailing? 	mustn't I have countervailed?
mustn't you have countervailed?
mustn't he have countervailed?
mustn't we have countervailed?
mustn't you have countervailed?
mustn't they have countervailed? 	mustn't I have been countervailing?
mustn't you have been countervailing?
mustn't he have been countervailing?
mustn't we have been countervailing?
mustn't you have been countervailing?
mustn't they have been countervailing?