I could flap you could flap she could flap we could flap you could flap they could flap
V-ing form
I could be flapping you could be flapping she could be flapping we could be flapping you could be flapping they could be flapping
Perfect
I could have flapped you could have flapped she could have flapped we could have flapped you could have flapped they could have flapped
V-ing perfect
I could have been flapping you could have been flapping she could have been flapping we could have been flapping you could have been flapping they could have been flapping
Negation
Simple form
I could not flap you could not flap she could not flap we could not flap you could not flap they could not flap
V-ing form
I could not be flapping you could not be flapping she could not be flapping we could not be flapping you could not be flapping they could not be flapping
Perfect
I could not have flapped you could not have flapped she could not have flapped we could not have flapped you could not have flapped they could not have flapped
V-ing perfect
I could not have been flapping you could not have been flapping she could not have been flapping we could not have been flapping you could not have been flapping they could not have been flapping
Interrogative form
Simple form
could I flap? could you flap? could she flap? could we flap? could you flap? could they flap?
V-ing form
could I be flapping? could you be flapping? could she be flapping? could we be flapping? could you be flapping? could they be flapping?
Perfect
could I have flapped? could you have flapped? could she have flapped? could we have flapped? could you have flapped? could they have flapped?
V-ing perfect
could I have been flapping? could you have been flapping? could she have been flapping? could we have been flapping? could you have been flapping? could they have been flapping?
Interro-negative form
Simple form
could I not flap? could you not flap? could she not flap? could we not flap? could you not flap? could they not flap?
V-ing form
could I not be flapping? could you not be flapping? could she not be flapping? could we not be flapping? could you not be flapping? could they not be flapping?
Perfect
could I not have flapped? could you not have flapped? could she not have flapped? could we not have flapped? could you not have flapped? could they not have flapped?
V-ing perfect
could I not have been flapping? could you not have been flapping? could she not have been flapping? could we not have been flapping? could you not have been flapping? could they not have been flapping?