English verb conjugation
CAN RUFF

Regular verb: ruff - ruffed - ruffed

Affirmation

Simple form	V-ing form
I can ruff you can ruff he can ruff we can ruff you can ruff they can ruff	I can be ruffing you can be ruffing he can be ruffing we can be ruffing you can be ruffing they can be ruffing
Perfect	V-ing perfect
I can have ruffed you can have ruffed he can have ruffed we can have ruffed you can have ruffed they can have ruffed	I can have been ruffing you can have been ruffing he can have been ruffing we can have been ruffing you can have been ruffing they can have been ruffing

Negation

Simple form	V-ing form
I can't ruff you can't ruff he can't ruff we can't ruff you can't ruff they can't ruff	I can't be ruffing you can't be ruffing he can't be ruffing we can't be ruffing you can't be ruffing they can't be ruffing
Perfect	V-ing perfect
I can't have ruffed you can't have ruffed he can't have ruffed we can't have ruffed you can't have ruffed they can't have ruffed	I can't have been ruffing you can't have been ruffing he can't have been ruffing we can't have been ruffing you can't have been ruffing they can't have been ruffing

Interrogative form

Simple form	V-ing form
can I ruff? can you ruff? can he ruff? can we ruff? can you ruff? can they ruff?	can I be ruffing? can you be ruffing? can he be ruffing? can we be ruffing? can you be ruffing? can they be ruffing?
Perfect	V-ing perfect
can I have ruffed? can you have ruffed? can he have ruffed? can we have ruffed? can you have ruffed? can they have ruffed?	can I have been ruffing? can you have been ruffing? can he have been ruffing? can we have been ruffing? can you have been ruffing? can they have been ruffing?

Interro-negative form

Simple form	V-ing form
can't I ruff? can't you ruff? can't he ruff? can't we ruff? can't you ruff? can't they ruff?	can't I be ruffing? can't you be ruffing? can't he be ruffing? can't we be ruffing? can't you be ruffing? can't they be ruffing?
Perfect	V-ing perfect
can't I have ruffed? can't you have ruffed? can't he have ruffed? can't we have ruffed? can't you have ruffed? can't they have ruffed?	can't I have been ruffing? can't you have been ruffing? can't he have been ruffing? can't we have been ruffing? can't you have been ruffing? can't they have been ruffing?