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