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