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