I ought to filter you ought to filter he ought to filter we ought to filter you ought to filter they ought to filter
V-ing form
I ought to be filtering you ought to be filtering he ought to be filtering we ought to be filtering you ought to be filtering they ought to be filtering
Perfect
I ought to have filtered you ought to have filtered he ought to have filtered we ought to have filtered you ought to have filtered they ought to have filtered
V-ing perfect
I ought to have been filtering you ought to have been filtering he ought to have been filtering we ought to have been filtering you ought to have been filtering they ought to have been filtering
Negation
Simple form
I oughtn't to filter you oughtn't to filter he oughtn't to filter we oughtn't to filter you oughtn't to filter they oughtn't to filter
V-ing form
I oughtn't to be filtering you oughtn't to be filtering he oughtn't to be filtering we oughtn't to be filtering you oughtn't to be filtering they oughtn't to be filtering
Perfect
I oughtn't to have filtered you oughtn't to have filtered he oughtn't to have filtered we oughtn't to have filtered you oughtn't to have filtered they oughtn't to have filtered
V-ing perfect
I oughtn't to have been filtering you oughtn't to have been filtering he oughtn't to have been filtering we oughtn't to have been filtering you oughtn't to have been filtering they oughtn't to have been filtering
Interrogative form
Simple form
ought to I filter? ought to you filter? ought to he filter? ought to we filter? ought to you filter? ought to they filter?
V-ing form
ought to I be filtering? ought to you be filtering? ought to he be filtering? ought to we be filtering? ought to you be filtering? ought to they be filtering?
Perfect
ought to I have filtered? ought to you have filtered? ought to he have filtered? ought to we have filtered? ought to you have filtered? ought to they have filtered?
V-ing perfect
ought to I have been filtering? ought to you have been filtering? ought to he have been filtering? ought to we have been filtering? ought to you have been filtering? ought to they have been filtering?
Interro-negative form
Simple form
oughtn't I to filter? oughtn't you to filter? oughtn't he to filter? oughtn't we to filter? oughtn't you to filter? oughtn't they to filter?
V-ing form
oughtn't I to be filtering? oughtn't you to be filtering? oughtn't he to be filtering? oughtn't we to be filtering? oughtn't you to be filtering? oughtn't they to be filtering?
Perfect
oughtn't I to have filtered? oughtn't you to have filtered? oughtn't he to have filtered? oughtn't we to have filtered? oughtn't you to have filtered? oughtn't they to have filtered?
V-ing perfect
oughtn't I to have been filtering? oughtn't you to have been filtering? oughtn't he to have been filtering? oughtn't we to have been filtering? oughtn't you to have been filtering? oughtn't they to have been filtering?