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 couldn't nicker you couldn't nicker he couldn't nicker we couldn't nicker you couldn't nicker they couldn't nicker
V-ing form
I couldn't be nickering you couldn't be nickering he couldn't be nickering we couldn't be nickering you couldn't be nickering they couldn't be nickering
Perfect
I couldn't have nickered you couldn't have nickered he couldn't have nickered we couldn't have nickered you couldn't have nickered they couldn't have nickered
V-ing perfect
I couldn't have been nickering you couldn't have been nickering he couldn't have been nickering we couldn't have been nickering you couldn't have been nickering they couldn't 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
couldn't I nicker? couldn't you nicker? couldn't he nicker? couldn't we nicker? couldn't you nicker? couldn't they nicker?
V-ing form
couldn't I be nickering? couldn't you be nickering? couldn't he be nickering? couldn't we be nickering? couldn't you be nickering? couldn't they be nickering?
Perfect
couldn't I have nickered? couldn't you have nickered? couldn't he have nickered? couldn't we have nickered? couldn't you have nickered? couldn't they have nickered?
V-ing perfect
couldn't I have been nickering? couldn't you have been nickering? couldn't he have been nickering? couldn't we have been nickering? couldn't you have been nickering? couldn't they have been nickering?