I could umber you could umber she could umber we could umber you could umber they could umber
V-ing form
I could be umbering you could be umbering she could be umbering we could be umbering you could be umbering they could be umbering
Perfect
I could have umbered you could have umbered she could have umbered we could have umbered you could have umbered they could have umbered
V-ing perfect
I could have been umbering you could have been umbering she could have been umbering we could have been umbering you could have been umbering they could have been umbering
Negation
Simple form
I could not umber you could not umber she could not umber we could not umber you could not umber they could not umber
V-ing form
I could not be umbering you could not be umbering she could not be umbering we could not be umbering you could not be umbering they could not be umbering
Perfect
I could not have umbered you could not have umbered she could not have umbered we could not have umbered you could not have umbered they could not have umbered
V-ing perfect
I could not have been umbering you could not have been umbering she could not have been umbering we could not have been umbering you could not have been umbering they could not have been umbering
Interrogative form
Simple form
could I umber? could you umber? could she umber? could we umber? could you umber? could they umber?
V-ing form
could I be umbering? could you be umbering? could she be umbering? could we be umbering? could you be umbering? could they be umbering?
Perfect
could I have umbered? could you have umbered? could she have umbered? could we have umbered? could you have umbered? could they have umbered?
V-ing perfect
could I have been umbering? could you have been umbering? could she have been umbering? could we have been umbering? could you have been umbering? could they have been umbering?
Interro-negative form
Simple form
could I not umber? could you not umber? could she not umber? could we not umber? could you not umber? could they not umber?
V-ing form
could I not be umbering? could you not be umbering? could she not be umbering? could we not be umbering? could you not be umbering? could they not be umbering?
Perfect
could I not have umbered? could you not have umbered? could she not have umbered? could we not have umbered? could you not have umbered? could they not have umbered?
V-ing perfect
could I not have been umbering? could you not have been umbering? could she not have been umbering? could we not have been umbering? could you not have been umbering? could they not have been umbering?