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