I could dim you could dim she could dim we could dim you could dim they could dim
V-ing form
I could be dimming you could be dimming she could be dimming we could be dimming you could be dimming they could be dimming
Perfect
I could have dimmed you could have dimmed she could have dimmed we could have dimmed you could have dimmed they could have dimmed
V-ing perfect
I could have been dimming you could have been dimming she could have been dimming we could have been dimming you could have been dimming they could have been dimming
Negation
Simple form
I couldn't dim you couldn't dim she couldn't dim we couldn't dim you couldn't dim they couldn't dim
V-ing form
I couldn't be dimming you couldn't be dimming she couldn't be dimming we couldn't be dimming you couldn't be dimming they couldn't be dimming
Perfect
I couldn't have dimmed you couldn't have dimmed she couldn't have dimmed we couldn't have dimmed you couldn't have dimmed they couldn't have dimmed
V-ing perfect
I couldn't have been dimming you couldn't have been dimming she couldn't have been dimming we couldn't have been dimming you couldn't have been dimming they couldn't have been dimming
Interrogative form
Simple form
could I dim? could you dim? could she dim? could we dim? could you dim? could they dim?
V-ing form
could I be dimming? could you be dimming? could she be dimming? could we be dimming? could you be dimming? could they be dimming?
Perfect
could I have dimmed? could you have dimmed? could she have dimmed? could we have dimmed? could you have dimmed? could they have dimmed?
V-ing perfect
could I have been dimming? could you have been dimming? could she have been dimming? could we have been dimming? could you have been dimming? could they have been dimming?
Interro-negative form
Simple form
couldn't I dim? couldn't you dim? couldn't she dim? couldn't we dim? couldn't you dim? couldn't they dim?
V-ing form
couldn't I be dimming? couldn't you be dimming? couldn't she be dimming? couldn't we be dimming? couldn't you be dimming? couldn't they be dimming?
Perfect
couldn't I have dimmed? couldn't you have dimmed? couldn't she have dimmed? couldn't we have dimmed? couldn't you have dimmed? couldn't they have dimmed?
V-ing perfect
couldn't I have been dimming? couldn't you have been dimming? couldn't she have been dimming? couldn't we have been dimming? couldn't you have been dimming? couldn't they have been dimming?