I'd be preascertaining you'd be preascertaining he'd be preascertaining we'd be preascertaining you'd be preascertaining they'd be preascertaining
Perfect
I should've preascertained you should've preascertained he should've preascertained we should've preascertained you should've preascertained they should've preascertained
V-ing perfect
I should've been preascertaining you should've been preascertaining he should've been preascertaining we should've been preascertaining you should've been preascertaining they should've been preascertaining
Negation
Simple form
I shouldn't preascertain you shouldn't preascertain he shouldn't preascertain we shouldn't preascertain you shouldn't preascertain they shouldn't preascertain
V-ing form
I shouldn't be preascertaining you shouldn't be preascertaining he shouldn't be preascertaining we shouldn't be preascertaining you shouldn't be preascertaining they shouldn't be preascertaining
Perfect
I shouldn't have preascertained you shouldn't have preascertained he shouldn't have preascertained we shouldn't have preascertained you shouldn't have preascertained they shouldn't have preascertained
V-ing perfect
I shouldn't have been preascertaining you shouldn't have been preascertaining he shouldn't have been preascertaining we shouldn't have been preascertaining you shouldn't have been preascertaining they shouldn't have been preascertaining
Interrogative form
Simple form
should I preascertain? should you preascertain? should he preascertain? should we preascertain? should you preascertain? should they preascertain?
V-ing form
should I be preascertaining? should you be preascertaining? should he be preascertaining? should we be preascertaining? should you be preascertaining? should they be preascertaining?
Perfect
should I have preascertained? should you have preascertained? should he have preascertained? should we have preascertained? should you have preascertained? should they have preascertained?
V-ing perfect
should I have been preascertaining? should you have been preascertaining? should he have been preascertaining? should we have been preascertaining? should you have been preascertaining? should they have been preascertaining?
Interro-negative form
Simple form
shouldn't I preascertain? shouldn't you preascertain? shouldn't he preascertain? shouldn't we preascertain? shouldn't you preascertain? shouldn't they preascertain?
V-ing form
shouldn't I be preascertaining? shouldn't you be preascertaining? shouldn't he be preascertaining? shouldn't we be preascertaining? shouldn't you be preascertaining? shouldn't they be preascertaining?
Perfect
shouldn't I have preascertained? shouldn't you have preascertained? shouldn't he have preascertained? shouldn't we have preascertained? shouldn't you have preascertained? shouldn't they have preascertained?
V-ing perfect
shouldn't I have been preascertaining? shouldn't you have been preascertaining? shouldn't he have been preascertaining? shouldn't we have been preascertaining? shouldn't you have been preascertaining? shouldn't they have been preascertaining?