I could barn you could barn she could barn we could barn you could barn they could barn
V-ing form
I could be barning you could be barning she could be barning we could be barning you could be barning they could be barning
Perfect
I could have barned you could have barned she could have barned we could have barned you could have barned they could have barned
V-ing perfect
I could have been barning you could have been barning she could have been barning we could have been barning you could have been barning they could have been barning
Negation
Simple form
I could not barn you could not barn she could not barn we could not barn you could not barn they could not barn
V-ing form
I could not be barning you could not be barning she could not be barning we could not be barning you could not be barning they could not be barning
Perfect
I could not have barned you could not have barned she could not have barned we could not have barned you could not have barned they could not have barned
V-ing perfect
I could not have been barning you could not have been barning she could not have been barning we could not have been barning you could not have been barning they could not have been barning
Interrogative form
Simple form
could I barn? could you barn? could she barn? could we barn? could you barn? could they barn?
V-ing form
could I be barning? could you be barning? could she be barning? could we be barning? could you be barning? could they be barning?
Perfect
could I have barned? could you have barned? could she have barned? could we have barned? could you have barned? could they have barned?
V-ing perfect
could I have been barning? could you have been barning? could she have been barning? could we have been barning? could you have been barning? could they have been barning?
Interro-negative form
Simple form
could I not barn? could you not barn? could she not barn? could we not barn? could you not barn? could they not barn?
V-ing form
could I not be barning? could you not be barning? could she not be barning? could we not be barning? could you not be barning? could they not be barning?
Perfect
could I not have barned? could you not have barned? could she not have barned? could we not have barned? could you not have barned? could they not have barned?
V-ing perfect
could I not have been barning? could you not have been barning? could she not have been barning? could we not have been barning? could you not have been barning? could they not have been barning?