I could obtain you could obtain he could obtain we could obtain you could obtain they could obtain
V-ing form
I could be obtaining you could be obtaining he could be obtaining we could be obtaining you could be obtaining they could be obtaining
Perfect
I could have obtained you could have obtained he could have obtained we could have obtained you could have obtained they could have obtained
V-ing perfect
I could have been obtaining you could have been obtaining he could have been obtaining we could have been obtaining you could have been obtaining they could have been obtaining
Negation
Simple form
I could not obtain you could not obtain he could not obtain we could not obtain you could not obtain they could not obtain
V-ing form
I could not be obtaining you could not be obtaining he could not be obtaining we could not be obtaining you could not be obtaining they could not be obtaining
Perfect
I could not have obtained you could not have obtained he could not have obtained we could not have obtained you could not have obtained they could not have obtained
V-ing perfect
I could not have been obtaining you could not have been obtaining he could not have been obtaining we could not have been obtaining you could not have been obtaining they could not have been obtaining
Interrogative form
Simple form
could I obtain? could you obtain? could he obtain? could we obtain? could you obtain? could they obtain?
V-ing form
could I be obtaining? could you be obtaining? could he be obtaining? could we be obtaining? could you be obtaining? could they be obtaining?
Perfect
could I have obtained? could you have obtained? could he have obtained? could we have obtained? could you have obtained? could they have obtained?
V-ing perfect
could I have been obtaining? could you have been obtaining? could he have been obtaining? could we have been obtaining? could you have been obtaining? could they have been obtaining?
Interro-negative form
Simple form
could I not obtain? could you not obtain? could he not obtain? could we not obtain? could you not obtain? could they not obtain?
V-ing form
could I not be obtaining? could you not be obtaining? could he not be obtaining? could we not be obtaining? could you not be obtaining? could they not be obtaining?
Perfect
could I not have obtained? could you not have obtained? could he not have obtained? could we not have obtained? could you not have obtained? could they not have obtained?
V-ing perfect
could I not have been obtaining? could you not have been obtaining? could he not have been obtaining? could we not have been obtaining? could you not have been obtaining? could they not have been obtaining?