I can barb you can barb he can barb we can barb you can barb they can barb
V-ing form
I can be barbing you can be barbing he can be barbing we can be barbing you can be barbing they can be barbing
Perfect
I can have barbed you can have barbed he can have barbed we can have barbed you can have barbed they can have barbed
V-ing perfect
I can have been barbing you can have been barbing he can have been barbing we can have been barbing you can have been barbing they can have been barbing
Negation
Simple form
I cannot barb you cannot barb he cannot barb we cannot barb you cannot barb they cannot barb
V-ing form
I cannot be barbing you cannot be barbing he cannot be barbing we cannot be barbing you cannot be barbing they cannot be barbing
Perfect
I cannot have barbed you cannot have barbed he cannot have barbed we cannot have barbed you cannot have barbed they cannot have barbed
V-ing perfect
I cannot have been barbing you cannot have been barbing he cannot have been barbing we cannot have been barbing you cannot have been barbing they cannot have been barbing
Interrogative form
Simple form
can I barb? can you barb? can he barb? can we barb? can you barb? can they barb?
V-ing form
can I be barbing? can you be barbing? can he be barbing? can we be barbing? can you be barbing? can they be barbing?
Perfect
can I have barbed? can you have barbed? can he have barbed? can we have barbed? can you have barbed? can they have barbed?
V-ing perfect
can I have been barbing? can you have been barbing? can he have been barbing? can we have been barbing? can you have been barbing? can they have been barbing?
Interro-negative form
Simple form
can I not barb? can you not barb? can he not barb? can we not barb? can you not barb? can they not barb?
V-ing form
can I not be barbing? can you not be barbing? can he not be barbing? can we not be barbing? can you not be barbing? can they not be barbing?
Perfect
can I not have barbed? can you not have barbed? can he not have barbed? can we not have barbed? can you not have barbed? can they not have barbed?
V-ing perfect
can I not have been barbing? can you not have been barbing? can he not have been barbing? can we not have been barbing? can you not have been barbing? can they not have been barbing?