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