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