I could layer you could layer she could layer we could layer you could layer they could layer
V-ing form
I could be layering you could be layering she could be layering we could be layering you could be layering they could be layering
Perfect
I could have layered you could have layered she could have layered we could have layered you could have layered they could have layered
V-ing perfect
I could have been layering you could have been layering she could have been layering we could have been layering you could have been layering they could have been layering
Negation
Simple form
I could not layer you could not layer she could not layer we could not layer you could not layer they could not layer
V-ing form
I could not be layering you could not be layering she could not be layering we could not be layering you could not be layering they could not be layering
Perfect
I could not have layered you could not have layered she could not have layered we could not have layered you could not have layered they could not have layered
V-ing perfect
I could not have been layering you could not have been layering she could not have been layering we could not have been layering you could not have been layering they could not have been layering
Interrogative form
Simple form
could I layer? could you layer? could she layer? could we layer? could you layer? could they layer?
V-ing form
could I be layering? could you be layering? could she be layering? could we be layering? could you be layering? could they be layering?
Perfect
could I have layered? could you have layered? could she have layered? could we have layered? could you have layered? could they have layered?
V-ing perfect
could I have been layering? could you have been layering? could she have been layering? could we have been layering? could you have been layering? could they have been layering?
Interro-negative form
Simple form
could I not layer? could you not layer? could she not layer? could we not layer? could you not layer? could they not layer?
V-ing form
could I not be layering? could you not be layering? could she not be layering? could we not be layering? could you not be layering? could they not be layering?
Perfect
could I not have layered? could you not have layered? could she not have layered? could we not have layered? could you not have layered? could they not have layered?
V-ing perfect
could I not have been layering? could you not have been layering? could she not have been layering? could we not have been layering? could you not have been layering? could they not have been layering?