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