ought to ascertain
Regular verb: ascertain - ascertained- ascertained

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I oughtn't to ascertain
you oughtn't to ascertain
she oughtn't to ascertain
we oughtn't to ascertain
you oughtn't to ascertain
they oughtn't to ascertain 	I oughtn't to be ascertaining
you oughtn't to be ascertaining
she oughtn't to be ascertaining
we oughtn't to be ascertaining
you oughtn't to be ascertaining
they oughtn't to be ascertaining	I oughtn't to have ascertained
you oughtn't to have ascertained
she oughtn't to have ascertained
we oughtn't to have ascertained
you oughtn't to have ascertained
they oughtn't to have ascertained	I oughtn't to have been ascertaining
you oughtn't to have been ascertaining
she oughtn't to have been ascertaining
we oughtn't to have been ascertaining
you oughtn't to have been ascertaining
they oughtn't to have been ascertaining	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
oughtn't I to ascertain?
oughtn't you to ascertain?
oughtn't she to ascertain?
oughtn't we to ascertain?
oughtn't you to ascertain?
oughtn't they to ascertain? 	oughtn't I to be ascertaining?
oughtn't you to be ascertaining?
oughtn't she to be ascertaining?
oughtn't we to be ascertaining?
oughtn't you to be ascertaining?
oughtn't they to be ascertaining? 	oughtn't I to have ascertained?
oughtn't you to have ascertained?
oughtn't she to have ascertained?
oughtn't we to have ascertained?
oughtn't you to have ascertained?
oughtn't they to have ascertained? 	oughtn't I to have been ascertaining?
oughtn't you to have been ascertaining?
oughtn't she to have been ascertaining?
oughtn't we to have been ascertaining?
oughtn't you to have been ascertaining?
oughtn't they to have been ascertaining?