I could kitten you could kitten he could kitten we could kitten you could kitten they could kitten
V-ing form
I could be kittening you could be kittening he could be kittening we could be kittening you could be kittening they could be kittening
Perfect
I could have kittened you could have kittened he could have kittened we could have kittened you could have kittened they could have kittened
V-ing perfect
I could have been kittening you could have been kittening he could have been kittening we could have been kittening you could have been kittening they could have been kittening
Negation
Simple form
I could not kitten you could not kitten he could not kitten we could not kitten you could not kitten they could not kitten
V-ing form
I could not be kittening you could not be kittening he could not be kittening we could not be kittening you could not be kittening they could not be kittening
Perfect
I could not have kittened you could not have kittened he could not have kittened we could not have kittened you could not have kittened they could not have kittened
V-ing perfect
I could not have been kittening you could not have been kittening he could not have been kittening we could not have been kittening you could not have been kittening they could not have been kittening
Interrogative form
Simple form
could I kitten? could you kitten? could he kitten? could we kitten? could you kitten? could they kitten?
V-ing form
could I be kittening? could you be kittening? could he be kittening? could we be kittening? could you be kittening? could they be kittening?
Perfect
could I have kittened? could you have kittened? could he have kittened? could we have kittened? could you have kittened? could they have kittened?
V-ing perfect
could I have been kittening? could you have been kittening? could he have been kittening? could we have been kittening? could you have been kittening? could they have been kittening?
Interro-negative form
Simple form
could I not kitten? could you not kitten? could he not kitten? could we not kitten? could you not kitten? could they not kitten?
V-ing form
could I not be kittening? could you not be kittening? could he not be kittening? could we not be kittening? could you not be kittening? could they not be kittening?
Perfect
could I not have kittened? could you not have kittened? could he not have kittened? could we not have kittened? could you not have kittened? could they not have kittened?
V-ing perfect
could I not have been kittening? could you not have been kittening? could he not have been kittening? could we not have been kittening? could you not have been kittening? could they not have been kittening?