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 couldn't fly you couldn't fly he couldn't fly we couldn't fly you couldn't fly they couldn't fly
V-ing form
I couldn't be flying you couldn't be flying he couldn't be flying we couldn't be flying you couldn't be flying they couldn't be flying
Perfect
I couldn't have flown you couldn't have flown he couldn't have flown we couldn't have flown you couldn't have flown they couldn't have flown
V-ing perfect
I couldn't have been flying you couldn't have been flying he couldn't have been flying we couldn't have been flying you couldn't have been flying they couldn't 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
couldn't I fly? couldn't you fly? couldn't he fly? couldn't we fly? couldn't you fly? couldn't they fly?
V-ing form
couldn't I be flying? couldn't you be flying? couldn't he be flying? couldn't we be flying? couldn't you be flying? couldn't they be flying?
Perfect
couldn't I have flown? couldn't you have flown? couldn't he have flown? couldn't we have flown? couldn't you have flown? couldn't they have flown?
V-ing perfect
couldn't I have been flying? couldn't you have been flying? couldn't he have been flying? couldn't we have been flying? couldn't you have been flying? couldn't they have been flying?