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