English verb conjugation
MUST ASCERTAIN

Regular verb: ascertain - ascertained - ascertained

Affirmation

Simple form	V-ing form
I must ascertain you must ascertain she must ascertain we must ascertain you must ascertain they must ascertain	I must be ascertaining you must be ascertaining she must be ascertaining we must be ascertaining you must be ascertaining they must be ascertaining
Perfect	V-ing perfect
I must have ascertained you must have ascertained she 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 she must have been ascertaining we must have been ascertaining you must have been ascertaining they must have been ascertaining

Negation

Simple form	V-ing form
I must not ascertain you must not ascertain she must not ascertain we must not ascertain you must not ascertain they must not ascertain	I must not be ascertaining you must not be ascertaining she must not be ascertaining we must not be ascertaining you must not be ascertaining they must not be ascertaining
Perfect	V-ing perfect
I must not have ascertained you must not have ascertained she must not have ascertained we must not have ascertained you must not have ascertained they must not have ascertained	I must not have been ascertaining you must not have been ascertaining she must not have been ascertaining we must not have been ascertaining you must not have been ascertaining they must not have been ascertaining

Interrogative form

Simple form	V-ing form
must I ascertain? must you ascertain? must she ascertain? must we ascertain? must you ascertain? must they ascertain?	must I be ascertaining? must you be ascertaining? must she be ascertaining? must we be ascertaining? must you be ascertaining? must they be ascertaining?
Perfect	V-ing perfect
must I have ascertained? must you have ascertained? must she 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 she have been ascertaining? must we have been ascertaining? must you have been ascertaining? must they have been ascertaining?

Interro-negative form

Simple form	V-ing form
must I not ascertain? must you not ascertain? must she not ascertain? must we not ascertain? must you not ascertain? must they not ascertain?	must I not be ascertaining? must you not be ascertaining? must she not be ascertaining? must we not be ascertaining? must you not be ascertaining? must they not be ascertaining?
Perfect	V-ing perfect
must I not have ascertained? must you not have ascertained? must she not have ascertained? must we not have ascertained? must you not have ascertained? must they not have ascertained?	must I not have been ascertaining? must you not have been ascertaining? must she not have been ascertaining? must we not have been ascertaining? must you not have been ascertaining? must they not have been ascertaining?