English verb conjugation
CAN ASCERTAIN

Regular verb: ascertain - ascertained - ascertained

Affirmation

Simple form	V-ing form
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
Perfect	V-ing 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	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

Negation

Simple form	V-ing form
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
Perfect	V-ing 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	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

Interrogative form

Simple form	V-ing form
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?
Perfect	V-ing 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?	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?

Interro-negative form

Simple form	V-ing form
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?
Perfect	V-ing 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?	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?