I could leather you could leather she could leather we could leather you could leather they could leather
V-ing form
I could be leathering you could be leathering she could be leathering we could be leathering you could be leathering they could be leathering
Perfect
I could have leathered you could have leathered she could have leathered we could have leathered you could have leathered they could have leathered
V-ing perfect
I could have been leathering you could have been leathering she could have been leathering we could have been leathering you could have been leathering they could have been leathering
Negation
Simple form
I could not leather you could not leather she could not leather we could not leather you could not leather they could not leather
V-ing form
I could not be leathering you could not be leathering she could not be leathering we could not be leathering you could not be leathering they could not be leathering
Perfect
I could not have leathered you could not have leathered she could not have leathered we could not have leathered you could not have leathered they could not have leathered
V-ing perfect
I could not have been leathering you could not have been leathering she could not have been leathering we could not have been leathering you could not have been leathering they could not have been leathering
Interrogative form
Simple form
could I leather? could you leather? could she leather? could we leather? could you leather? could they leather?
V-ing form
could I be leathering? could you be leathering? could she be leathering? could we be leathering? could you be leathering? could they be leathering?
Perfect
could I have leathered? could you have leathered? could she have leathered? could we have leathered? could you have leathered? could they have leathered?
V-ing perfect
could I have been leathering? could you have been leathering? could she have been leathering? could we have been leathering? could you have been leathering? could they have been leathering?
Interro-negative form
Simple form
could I not leather? could you not leather? could she not leather? could we not leather? could you not leather? could they not leather?
V-ing form
could I not be leathering? could you not be leathering? could she not be leathering? could we not be leathering? could you not be leathering? could they not be leathering?
Perfect
could I not have leathered? could you not have leathered? could she not have leathered? could we not have leathered? could you not have leathered? could they not have leathered?
V-ing perfect
could I not have been leathering? could you not have been leathering? could she not have been leathering? could we not have been leathering? could you not have been leathering? could they not have been leathering?