I could nicker you could nicker he could nicker we could nicker you could nicker they could nicker
V-ing form
I could be nickering you could be nickering he could be nickering we could be nickering you could be nickering they could be nickering
Perfect
I could have nickered you could have nickered he could have nickered we could have nickered you could have nickered they could have nickered
V-ing perfect
I could have been nickering you could have been nickering he could have been nickering we could have been nickering you could have been nickering they could have been nickering
Negation
Simple form
I could not nicker you could not nicker he could not nicker we could not nicker you could not nicker they could not nicker
V-ing form
I could not be nickering you could not be nickering he could not be nickering we could not be nickering you could not be nickering they could not be nickering
Perfect
I could not have nickered you could not have nickered he could not have nickered we could not have nickered you could not have nickered they could not have nickered
V-ing perfect
I could not have been nickering you could not have been nickering he could not have been nickering we could not have been nickering you could not have been nickering they could not have been nickering
Interrogative form
Simple form
could I nicker? could you nicker? could he nicker? could we nicker? could you nicker? could they nicker?
V-ing form
could I be nickering? could you be nickering? could he be nickering? could we be nickering? could you be nickering? could they be nickering?
Perfect
could I have nickered? could you have nickered? could he have nickered? could we have nickered? could you have nickered? could they have nickered?
V-ing perfect
could I have been nickering? could you have been nickering? could he have been nickering? could we have been nickering? could you have been nickering? could they have been nickering?
Interro-negative form
Simple form
could I not nicker? could you not nicker? could he not nicker? could we not nicker? could you not nicker? could they not nicker?
V-ing form
could I not be nickering? could you not be nickering? could he not be nickering? could we not be nickering? could you not be nickering? could they not be nickering?
Perfect
could I not have nickered? could you not have nickered? could he not have nickered? could we not have nickered? could you not have nickered? could they not have nickered?
V-ing perfect
could I not have been nickering? could you not have been nickering? could he not have been nickering? could we not have been nickering? could you not have been nickering? could they not have been nickering?