English verb conjugation
MUST PREASCERTAIN

Regular verb: preascertain - preascertained - preascertained

Affirmation

Simple form	V-ing form
I must preascertain you must preascertain he must preascertain we must preascertain you must preascertain they must preascertain	I must be preascertaining you must be preascertaining he must be preascertaining we must be preascertaining you must be preascertaining they must be preascertaining
Perfect	V-ing perfect
I must have preascertained you must have preascertained he must have preascertained we must have preascertained you must have preascertained they must have preascertained	I must have been preascertaining you must have been preascertaining he must have been preascertaining we must have been preascertaining you must have been preascertaining they must have been preascertaining

Negation

Simple form	V-ing form
I mustn't preascertain you mustn't preascertain he mustn't preascertain we mustn't preascertain you mustn't preascertain they mustn't preascertain	I mustn't be preascertaining you mustn't be preascertaining he mustn't be preascertaining we mustn't be preascertaining you mustn't be preascertaining they mustn't be preascertaining
Perfect	V-ing perfect
I mustn't have preascertained you mustn't have preascertained he mustn't have preascertained we mustn't have preascertained you mustn't have preascertained they mustn't have preascertained	I mustn't have been preascertaining you mustn't have been preascertaining he mustn't have been preascertaining we mustn't have been preascertaining you mustn't have been preascertaining they mustn't have been preascertaining

Interrogative form

Simple form	V-ing form
must I preascertain? must you preascertain? must he preascertain? must we preascertain? must you preascertain? must they preascertain?	must I be preascertaining? must you be preascertaining? must he be preascertaining? must we be preascertaining? must you be preascertaining? must they be preascertaining?
Perfect	V-ing perfect
must I have preascertained? must you have preascertained? must he have preascertained? must we have preascertained? must you have preascertained? must they have preascertained?	must I have been preascertaining? must you have been preascertaining? must he have been preascertaining? must we have been preascertaining? must you have been preascertaining? must they have been preascertaining?

Interro-negative form

Simple form	V-ing form
mustn't I preascertain? mustn't you preascertain? mustn't he preascertain? mustn't we preascertain? mustn't you preascertain? mustn't they preascertain?	mustn't I be preascertaining? mustn't you be preascertaining? mustn't he be preascertaining? mustn't we be preascertaining? mustn't you be preascertaining? mustn't they be preascertaining?
Perfect	V-ing perfect
mustn't I have preascertained? mustn't you have preascertained? mustn't he have preascertained? mustn't we have preascertained? mustn't you have preascertained? mustn't they have preascertained?	mustn't I have been preascertaining? mustn't you have been preascertaining? mustn't he have been preascertaining? mustn't we have been preascertaining? mustn't you have been preascertaining? mustn't they have been preascertaining?