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