I could dim you could dim he could dim we could dim you could dim they could dim
V-ing form
I could be dimming you could be dimming he could be dimming we could be dimming you could be dimming they could be dimming
Perfect
I could have dimmed you could have dimmed he 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 he 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 he 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 he 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 he 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 he 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 he dim? could we dim? could you dim? could they dim?
V-ing form
could I be dimming? could you be dimming? could he be dimming? could we be dimming? could you be dimming? could they be dimming?
Perfect
could I have dimmed? could you have dimmed? could he 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 he 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 he 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 he 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 he 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 he have been dimming? couldn't we have been dimming? couldn't you have been dimming? couldn't they have been dimming?