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 cannot ascertain you cannot ascertain he cannot ascertain we cannot ascertain you cannot ascertain they cannot ascertain	I cannot be ascertaining you cannot be ascertaining he cannot be ascertaining we cannot be ascertaining you cannot be ascertaining they cannot be ascertaining
Perfect	V-ing perfect
I cannot have ascertained you cannot have ascertained he cannot have ascertained we cannot have ascertained you cannot have ascertained they cannot have ascertained	I cannot have been ascertaining you cannot have been ascertaining he cannot have been ascertaining we cannot have been ascertaining you cannot have been ascertaining they cannot 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 I not ascertain? can you not ascertain? can he not ascertain? can we not ascertain? can you not ascertain? can they not ascertain?	can I not be ascertaining? can you not be ascertaining? can he not be ascertaining? can we not be ascertaining? can you not be ascertaining? can they not be ascertaining?
Perfect	V-ing perfect
can I not have ascertained? can you not have ascertained? can he not have ascertained? can we not have ascertained? can you not have ascertained? can they not have ascertained?	can I not have been ascertaining? can you not have been ascertaining? can he not have been ascertaining? can we not have been ascertaining? can you not have been ascertaining? can they not have been ascertaining?