must ascertain
Verbe régulier : ascertain - ascertained- ascertained
Traduction française : établir - constater 

Affirmation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I must ascertain
you must ascertain
he must ascertain
we must ascertain
you must ascertain
they must ascertain 	I must be ascertaining
you must be ascertaining
he must be ascertaining
we must be ascertaining
you must be ascertaining
they must be ascertaining	I must have ascertained
you must have ascertained
he must have ascertained
we must have ascertained
you must have ascertained
they must have ascertained	I must have been ascertaining
you must have been ascertaining
he must have been ascertaining
we must have been ascertaining
you must have been ascertaining
they must have been ascertaining	

Négation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I mustn't ascertain
you mustn't ascertain
he mustn't ascertain
we mustn't ascertain
you mustn't ascertain
they mustn't ascertain 	I mustn't be ascertaining
you mustn't be ascertaining
he mustn't be ascertaining
we mustn't be ascertaining
you mustn't be ascertaining
they mustn't be ascertaining	I mustn't have ascertained
you mustn't have ascertained
he mustn't have ascertained
we mustn't have ascertained
you mustn't have ascertained
they mustn't have ascertained	I mustn't have been ascertaining
you mustn't have been ascertaining
he mustn't have been ascertaining
we mustn't have been ascertaining
you mustn't have been ascertaining
they mustn't have been ascertaining	

Forme interrogative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
must I ascertain?
must you ascertain?
must he ascertain?
must we ascertain?
must you ascertain?
must they ascertain? 	must I be ascertaining?
must you be ascertaining?
must he be ascertaining?
must we be ascertaining?
must you be ascertaining?
must they be ascertaining? 	must I have ascertained?
must you have ascertained?
must he have ascertained?
must we have ascertained?
must you have ascertained?
must they have ascertained? 	must I have been ascertaining?
must you have been ascertaining?
must he have been ascertaining?
must we have been ascertaining?
must you have been ascertaining?
must they have been ascertaining? 	

Forme interro-négative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
mustn't I ascertain?
mustn't you ascertain?
mustn't he ascertain?
mustn't we ascertain?
mustn't you ascertain?
mustn't they ascertain? 	mustn't I be ascertaining?
mustn't you be ascertaining?
mustn't he be ascertaining?
mustn't we be ascertaining?
mustn't you be ascertaining?
mustn't they be ascertaining? 	mustn't I have ascertained?
mustn't you have ascertained?
mustn't he have ascertained?
mustn't we have ascertained?
mustn't you have ascertained?
mustn't they have ascertained? 	mustn't I have been ascertaining?
mustn't you have been ascertaining?
mustn't he have been ascertaining?
mustn't we have been ascertaining?
mustn't you have been ascertaining?
mustn't they have been ascertaining?