could preascertain
Regular verb: preascertain - preascertained- preascertained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could preascertain
you could preascertain
she could preascertain
we could preascertain
you could preascertain
they could preascertain 	I could be preascertaining
you could be preascertaining
she could be preascertaining
we could be preascertaining
you could be preascertaining
they could be preascertaining	I could have preascertained
you could have preascertained
she could have preascertained
we could have preascertained
you could have preascertained
they could have preascertained	I could have been preascertaining
you could have been preascertaining
she could have been preascertaining
we could have been preascertaining
you could have been preascertaining
they could have been preascertaining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't preascertain
you couldn't preascertain
she couldn't preascertain
we couldn't preascertain
you couldn't preascertain
they couldn't preascertain 	I couldn't be preascertaining
you couldn't be preascertaining
she couldn't be preascertaining
we couldn't be preascertaining
you couldn't be preascertaining
they couldn't be preascertaining	I couldn't have preascertained
you couldn't have preascertained
she couldn't have preascertained
we couldn't have preascertained
you couldn't have preascertained
they couldn't have preascertained	I couldn't have been preascertaining
you couldn't have been preascertaining
she couldn't have been preascertaining
we couldn't have been preascertaining
you couldn't have been preascertaining
they couldn't have been preascertaining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I preascertain?
could you preascertain?
could she preascertain?
could we preascertain?
could you preascertain?
could they preascertain? 	could I be preascertaining?
could you be preascertaining?
could she be preascertaining?
could we be preascertaining?
could you be preascertaining?
could they be preascertaining? 	could I have preascertained?
could you have preascertained?
could she have preascertained?
could we have preascertained?
could you have preascertained?
could they have preascertained? 	could I have been preascertaining?
could you have been preascertaining?
could she have been preascertaining?
could we have been preascertaining?
could you have been preascertaining?
could they have been preascertaining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I preascertain?
couldn't you preascertain?
couldn't she preascertain?
couldn't we preascertain?
couldn't you preascertain?
couldn't they preascertain? 	couldn't I be preascertaining?
couldn't you be preascertaining?
couldn't she be preascertaining?
couldn't we be preascertaining?
couldn't you be preascertaining?
couldn't they be preascertaining? 	couldn't I have preascertained?
couldn't you have preascertained?
couldn't she have preascertained?
couldn't we have preascertained?
couldn't you have preascertained?
couldn't they have preascertained? 	couldn't I have been preascertaining?
couldn't you have been preascertaining?
couldn't she have been preascertaining?
couldn't we have been preascertaining?
couldn't you have been preascertaining?
couldn't they have been preascertaining?