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