I could background you could background he could background we could background you could background they could background
V-ing form
I could be backgrounding you could be backgrounding he could be backgrounding we could be backgrounding you could be backgrounding they could be backgrounding
Perfect
I could have backgrounded you could have backgrounded he could have backgrounded we could have backgrounded you could have backgrounded they could have backgrounded
V-ing perfect
I could have been backgrounding you could have been backgrounding he could have been backgrounding we could have been backgrounding you could have been backgrounding they could have been backgrounding
Negation
Simple form
I could not background you could not background he could not background we could not background you could not background they could not background
V-ing form
I could not be backgrounding you could not be backgrounding he could not be backgrounding we could not be backgrounding you could not be backgrounding they could not be backgrounding
Perfect
I could not have backgrounded you could not have backgrounded he could not have backgrounded we could not have backgrounded you could not have backgrounded they could not have backgrounded
V-ing perfect
I could not have been backgrounding you could not have been backgrounding he could not have been backgrounding we could not have been backgrounding you could not have been backgrounding they could not have been backgrounding
Interrogative form
Simple form
could I background? could you background? could he background? could we background? could you background? could they background?
V-ing form
could I be backgrounding? could you be backgrounding? could he be backgrounding? could we be backgrounding? could you be backgrounding? could they be backgrounding?
Perfect
could I have backgrounded? could you have backgrounded? could he have backgrounded? could we have backgrounded? could you have backgrounded? could they have backgrounded?
V-ing perfect
could I have been backgrounding? could you have been backgrounding? could he have been backgrounding? could we have been backgrounding? could you have been backgrounding? could they have been backgrounding?
Interro-negative form
Simple form
could I not background? could you not background? could he not background? could we not background? could you not background? could they not background?
V-ing form
could I not be backgrounding? could you not be backgrounding? could he not be backgrounding? could we not be backgrounding? could you not be backgrounding? could they not be backgrounding?
Perfect
could I not have backgrounded? could you not have backgrounded? could he not have backgrounded? could we not have backgrounded? could you not have backgrounded? could they not have backgrounded?
V-ing perfect
could I not have been backgrounding? could you not have been backgrounding? could he not have been backgrounding? could we not have been backgrounding? could you not have been backgrounding? could they not have been backgrounding?