I could barb you could barb he could barb we could barb you could barb they could barb
V-ing form
I could be barbing you could be barbing he could be barbing we could be barbing you could be barbing they could be barbing
Perfect
I could have barbed you could have barbed he could have barbed we could have barbed you could have barbed they could have barbed
V-ing perfect
I could have been barbing you could have been barbing he could have been barbing we could have been barbing you could have been barbing they could have been barbing
Negation
Simple form
I couldn't barb you couldn't barb he couldn't barb we couldn't barb you couldn't barb they couldn't barb
V-ing form
I couldn't be barbing you couldn't be barbing he couldn't be barbing we couldn't be barbing you couldn't be barbing they couldn't be barbing
Perfect
I couldn't have barbed you couldn't have barbed he couldn't have barbed we couldn't have barbed you couldn't have barbed they couldn't have barbed
V-ing perfect
I couldn't have been barbing you couldn't have been barbing he couldn't have been barbing we couldn't have been barbing you couldn't have been barbing they couldn't have been barbing
Interrogative form
Simple form
could I barb? could you barb? could he barb? could we barb? could you barb? could they barb?
V-ing form
could I be barbing? could you be barbing? could he be barbing? could we be barbing? could you be barbing? could they be barbing?
Perfect
could I have barbed? could you have barbed? could he have barbed? could we have barbed? could you have barbed? could they have barbed?
V-ing perfect
could I have been barbing? could you have been barbing? could he have been barbing? could we have been barbing? could you have been barbing? could they have been barbing?
Interro-negative form
Simple form
couldn't I barb? couldn't you barb? couldn't he barb? couldn't we barb? couldn't you barb? couldn't they barb?
V-ing form
couldn't I be barbing? couldn't you be barbing? couldn't he be barbing? couldn't we be barbing? couldn't you be barbing? couldn't they be barbing?
Perfect
couldn't I have barbed? couldn't you have barbed? couldn't he have barbed? couldn't we have barbed? couldn't you have barbed? couldn't they have barbed?
V-ing perfect
couldn't I have been barbing? couldn't you have been barbing? couldn't he have been barbing? couldn't we have been barbing? couldn't you have been barbing? couldn't they have been barbing?