ought to strengthen
Regular verb: strengthen - strengthened- strengthened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I ought to strengthen
you ought to strengthen
she ought to strengthen
we ought to strengthen
you ought to strengthen
they ought to strengthen 	I ought to be strengthening
you ought to be strengthening
she ought to be strengthening
we ought to be strengthening
you ought to be strengthening
they ought to be strengthening	I ought to have strengthened
you ought to have strengthened
she ought to have strengthened
we ought to have strengthened
you ought to have strengthened
they ought to have strengthened	I ought to have been strengthening
you ought to have been strengthening
she ought to have been strengthening
we ought to have been strengthening
you ought to have been strengthening
they ought to have been strengthening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I oughtn't to strengthen
you oughtn't to strengthen
she oughtn't to strengthen
we oughtn't to strengthen
you oughtn't to strengthen
they oughtn't to strengthen 	I oughtn't to be strengthening
you oughtn't to be strengthening
she oughtn't to be strengthening
we oughtn't to be strengthening
you oughtn't to be strengthening
they oughtn't to be strengthening	I oughtn't to have strengthened
you oughtn't to have strengthened
she oughtn't to have strengthened
we oughtn't to have strengthened
you oughtn't to have strengthened
they oughtn't to have strengthened	I oughtn't to have been strengthening
you oughtn't to have been strengthening
she oughtn't to have been strengthening
we oughtn't to have been strengthening
you oughtn't to have been strengthening
they oughtn't to have been strengthening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
ought to I strengthen?
ought to you strengthen?
ought to she strengthen?
ought to we strengthen?
ought to you strengthen?
ought to they strengthen? 	ought to I be strengthening?
ought to you be strengthening?
ought to she be strengthening?
ought to we be strengthening?
ought to you be strengthening?
ought to they be strengthening? 	ought to I have strengthened?
ought to you have strengthened?
ought to she have strengthened?
ought to we have strengthened?
ought to you have strengthened?
ought to they have strengthened? 	ought to I have been strengthening?
ought to you have been strengthening?
ought to she have been strengthening?
ought to we have been strengthening?
ought to you have been strengthening?
ought to they have been strengthening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
oughtn't I to strengthen?
oughtn't you to strengthen?
oughtn't she to strengthen?
oughtn't we to strengthen?
oughtn't you to strengthen?
oughtn't they to strengthen? 	oughtn't I to be strengthening?
oughtn't you to be strengthening?
oughtn't she to be strengthening?
oughtn't we to be strengthening?
oughtn't you to be strengthening?
oughtn't they to be strengthening? 	oughtn't I to have strengthened?
oughtn't you to have strengthened?
oughtn't she to have strengthened?
oughtn't we to have strengthened?
oughtn't you to have strengthened?
oughtn't they to have strengthened? 	oughtn't I to have been strengthening?
oughtn't you to have been strengthening?
oughtn't she to have been strengthening?
oughtn't we to have been strengthening?
oughtn't you to have been strengthening?
oughtn't they to have been strengthening?