ought to preascertain
Regular verb: preascertain - preascertained- preascertained

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I ought not to preascertain
you ought not to preascertain
he ought not to preascertain
we ought not to preascertain
you ought not to preascertain
they ought not to preascertain 	I ought not to preascertaining
you ought not to preascertaining
he ought not to preascertaining
we ought not to preascertaining
you ought not to preascertaining
they ought not to preascertaining	I ought not to have preascertained
you ought not to have preascertained
he ought not to have preascertained
we ought not to have preascertained
you ought not to have preascertained
they ought not to have preascertained	I ought not to have been preascertaining
you ought not to have been preascertaining
he ought not to have been preascertaining
we ought not to have been preascertaining
you ought not to have been preascertaining
they ought not to have been preascertaining	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
ought I not to preascertain?
ought you not to preascertain?
ought he not to preascertain?
ought we not to preascertain?
ought you not to preascertain?
ought they not to preascertain? 	ought I not to be preascertaining?
ought you not to be preascertaining?
ought he not to be preascertaining?
ought we not to be preascertaining?
ought you not to be preascertaining?
ought they not to be preascertaining? 	ought I not to have preascertained?
ought you not to have preascertained?
ought he not to have preascertained?
ought we not to have preascertained?
ought you not to have preascertained?
ought they not to have preascertained? 	ought I not to have been preascertaining?
ought you not to have been preascertaining?
ought he not to have been preascertaining?
ought we not to have been preascertaining?
ought you not to have been preascertaining?
ought they not to have been preascertaining?