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