I could hammer you could hammer she could hammer we could hammer you could hammer they could hammer
V-ing form
I could be hammering you could be hammering she could be hammering we could be hammering you could be hammering they could be hammering
Perfect
I could have hammered you could have hammered she could have hammered we could have hammered you could have hammered they could have hammered
V-ing perfect
I could have been hammering you could have been hammering she could have been hammering we could have been hammering you could have been hammering they could have been hammering
Negation
Simple form
I could not hammer you could not hammer she could not hammer we could not hammer you could not hammer they could not hammer
V-ing form
I could not be hammering you could not be hammering she could not be hammering we could not be hammering you could not be hammering they could not be hammering
Perfect
I could not have hammered you could not have hammered she could not have hammered we could not have hammered you could not have hammered they could not have hammered
V-ing perfect
I could not have been hammering you could not have been hammering she could not have been hammering we could not have been hammering you could not have been hammering they could not have been hammering
Interrogative form
Simple form
could I hammer? could you hammer? could she hammer? could we hammer? could you hammer? could they hammer?
V-ing form
could I be hammering? could you be hammering? could she be hammering? could we be hammering? could you be hammering? could they be hammering?
Perfect
could I have hammered? could you have hammered? could she have hammered? could we have hammered? could you have hammered? could they have hammered?
V-ing perfect
could I have been hammering? could you have been hammering? could she have been hammering? could we have been hammering? could you have been hammering? could they have been hammering?
Interro-negative form
Simple form
could I not hammer? could you not hammer? could she not hammer? could we not hammer? could you not hammer? could they not hammer?
V-ing form
could I not be hammering? could you not be hammering? could she not be hammering? could we not be hammering? could you not be hammering? could they not be hammering?
Perfect
could I not have hammered? could you not have hammered? could she not have hammered? could we not have hammered? could you not have hammered? could they not have hammered?
V-ing perfect
could I not have been hammering? could you not have been hammering? could she not have been hammering? could we not have been hammering? could you not have been hammering? could they not have been hammering?