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 ought not to filter you ought not to filter he ought not to filter we ought not to filter you ought not to filter they ought not to filter
V-ing form
I ought not to filtering you ought not to filtering he ought not to filtering we ought not to filtering you ought not to filtering they ought not to filtering
Perfect
I ought not to have filtered you ought not to have filtered he ought not to have filtered we ought not to have filtered you ought not to have filtered they ought not to have filtered
V-ing perfect
I ought not to have been filtering you ought not to have been filtering he ought not to have been filtering we ought not to have been filtering you ought not to have been filtering they ought not 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
ought I not to filter? ought you not to filter? ought he not to filter? ought we not to filter? ought you not to filter? ought they not to filter?
V-ing form
ought I not to be filtering? ought you not to be filtering? ought he not to be filtering? ought we not to be filtering? ought you not to be filtering? ought they not to be filtering?
Perfect
ought I not to have filtered? ought you not to have filtered? ought he not to have filtered? ought we not to have filtered? ought you not to have filtered? ought they not to have filtered?
V-ing perfect
ought I not to have been filtering? ought you not to have been filtering? ought he not to have been filtering? ought we not to have been filtering? ought you not to have been filtering? ought they not to have been filtering?