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

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

Négation 	
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I can't ascertain
you can't ascertain
he can't ascertain
we can't ascertain
you can't ascertain
they can't ascertain 	I can't be ascertaining
you can't be ascertaining
he can't be ascertaining
we can't be ascertaining
you can't be ascertaining
they can't be ascertaining	I can't have ascertained
you can't have ascertained
he can't have ascertained
we can't have ascertained
you can't have ascertained
they can't have ascertained	I can't have been ascertaining
you can't have been ascertaining
he can't have been ascertaining
we can't have been ascertaining
you can't have been ascertaining
they can't have been ascertaining	

Forme interrogative 	
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can I ascertain?
can you ascertain?
can he ascertain?
can we ascertain?
can you ascertain?
can they ascertain? 	can I be ascertaining?
can you be ascertaining?
can he be ascertaining?
can we be ascertaining?
can you be ascertaining?
can they be ascertaining? 	can I have ascertained?
can you have ascertained?
can he have ascertained?
can we have ascertained?
can you have ascertained?
can they have ascertained? 	can I have been ascertaining?
can you have been ascertaining?
can he have been ascertaining?
can we have been ascertaining?
can you have been ascertaining?
can they have been ascertaining? 	

Forme interro-négative 	
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can't I ascertain?
can't you ascertain?
can't he ascertain?
can't we ascertain?
can't you ascertain?
can't they ascertain? 	can't I be ascertaining?
can't you be ascertaining?
can't he be ascertaining?
can't we be ascertaining?
can't you be ascertaining?
can't they be ascertaining? 	can't I have ascertained?
can't you have ascertained?
can't he have ascertained?
can't we have ascertained?
can't you have ascertained?
can't they have ascertained? 	can't I have been ascertaining?
can't you have been ascertaining?
can't he have been ascertaining?
can't we have been ascertaining?
can't you have been ascertaining?
can't they have been ascertaining?