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 couldn't layer you couldn't layer she couldn't layer we couldn't layer you couldn't layer they couldn't layer
V-ing form
I couldn't be layering you couldn't be layering she couldn't be layering we couldn't be layering you couldn't be layering they couldn't be layering
Perfect
I couldn't have layered you couldn't have layered she couldn't have layered we couldn't have layered you couldn't have layered they couldn't have layered
V-ing perfect
I couldn't have been layering you couldn't have been layering she couldn't have been layering we couldn't have been layering you couldn't have been layering they couldn't 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
couldn't I layer? couldn't you layer? couldn't she layer? couldn't we layer? couldn't you layer? couldn't they layer?
V-ing form
couldn't I be layering? couldn't you be layering? couldn't she be layering? couldn't we be layering? couldn't you be layering? couldn't they be layering?
Perfect
couldn't I have layered? couldn't you have layered? couldn't she have layered? couldn't we have layered? couldn't you have layered? couldn't they have layered?
V-ing perfect
couldn't I have been layering? couldn't you have been layering? couldn't she have been layering? couldn't we have been layering? couldn't you have been layering? couldn't they have been layering?