English verb conjugation
CAN PUFF

Regular verb: puff - puffed - puffed

Affirmation

Simple form	V-ing form
I can puff you can puff he can puff we can puff you can puff they can puff	I can be puffing you can be puffing he can be puffing we can be puffing you can be puffing they can be puffing
Perfect	V-ing perfect
I can have puffed you can have puffed he can have puffed we can have puffed you can have puffed they can have puffed	I can have been puffing you can have been puffing he can have been puffing we can have been puffing you can have been puffing they can have been puffing

Negation

Simple form	V-ing form
I cannot puff you cannot puff he cannot puff we cannot puff you cannot puff they cannot puff	I cannot be puffing you cannot be puffing he cannot be puffing we cannot be puffing you cannot be puffing they cannot be puffing
Perfect	V-ing perfect
I cannot have puffed you cannot have puffed he cannot have puffed we cannot have puffed you cannot have puffed they cannot have puffed	I cannot have been puffing you cannot have been puffing he cannot have been puffing we cannot have been puffing you cannot have been puffing they cannot have been puffing

Interrogative form

Simple form	V-ing form
can I puff? can you puff? can he puff? can we puff? can you puff? can they puff?	can I be puffing? can you be puffing? can he be puffing? can we be puffing? can you be puffing? can they be puffing?
Perfect	V-ing perfect
can I have puffed? can you have puffed? can he have puffed? can we have puffed? can you have puffed? can they have puffed?	can I have been puffing? can you have been puffing? can he have been puffing? can we have been puffing? can you have been puffing? can they have been puffing?

Interro-negative form

Simple form	V-ing form
can I not puff? can you not puff? can he not puff? can we not puff? can you not puff? can they not puff?	can I not be puffing? can you not be puffing? can he not be puffing? can we not be puffing? can you not be puffing? can they not be puffing?
Perfect	V-ing perfect
can I not have puffed? can you not have puffed? can he not have puffed? can we not have puffed? can you not have puffed? can they not have puffed?	can I not have been puffing? can you not have been puffing? can he not have been puffing? can we not have been puffing? can you not have been puffing? can they not have been puffing?