I could fly you could fly he could fly we could fly you could fly they could fly
V-ing form
I could be flying you could be flying he could be flying we could be flying you could be flying they could be flying
Perfect
I could have flown you could have flown he could have flown we could have flown you could have flown they could have flown
V-ing perfect
I could have been flying you could have been flying he could have been flying we could have been flying you could have been flying they could have been flying
Negation
Simple form
I could not fly you could not fly he could not fly we could not fly you could not fly they could not fly
V-ing form
I could not be flying you could not be flying he could not be flying we could not be flying you could not be flying they could not be flying
Perfect
I could not have flown you could not have flown he could not have flown we could not have flown you could not have flown they could not have flown
V-ing perfect
I could not have been flying you could not have been flying he could not have been flying we could not have been flying you could not have been flying they could not have been flying
Interrogative form
Simple form
could I fly? could you fly? could he fly? could we fly? could you fly? could they fly?
V-ing form
could I be flying? could you be flying? could he be flying? could we be flying? could you be flying? could they be flying?
Perfect
could I have flown? could you have flown? could he have flown? could we have flown? could you have flown? could they have flown?
V-ing perfect
could I have been flying? could you have been flying? could he have been flying? could we have been flying? could you have been flying? could they have been flying?
Interro-negative form
Simple form
could I not fly? could you not fly? could he not fly? could we not fly? could you not fly? could they not fly?
V-ing form
could I not be flying? could you not be flying? could he not be flying? could we not be flying? could you not be flying? could they not be flying?
Perfect
could I not have flown? could you not have flown? could he not have flown? could we not have flown? could you not have flown? could they not have flown?
V-ing perfect
could I not have been flying? could you not have been flying? could he not have been flying? could we not have been flying? could you not have been flying? could they not have been flying?