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