I could manage you could manage he could manage we could manage you could manage they could manage
V-ing form
I could be managing you could be managing he could be managing we could be managing you could be managing they could be managing
Perfect
I could have managed you could have managed he could have managed we could have managed you could have managed they could have managed
V-ing perfect
I could have been managing you could have been managing he could have been managing we could have been managing you could have been managing they could have been managing
Negation
Simple form
I could not manage you could not manage he could not manage we could not manage you could not manage they could not manage
V-ing form
I could not be managing you could not be managing he could not be managing we could not be managing you could not be managing they could not be managing
Perfect
I could not have managed you could not have managed he could not have managed we could not have managed you could not have managed they could not have managed
V-ing perfect
I could not have been managing you could not have been managing he could not have been managing we could not have been managing you could not have been managing they could not have been managing
Interrogative form
Simple form
could I manage? could you manage? could he manage? could we manage? could you manage? could they manage?
V-ing form
could I be managing? could you be managing? could he be managing? could we be managing? could you be managing? could they be managing?
Perfect
could I have managed? could you have managed? could he have managed? could we have managed? could you have managed? could they have managed?
V-ing perfect
could I have been managing? could you have been managing? could he have been managing? could we have been managing? could you have been managing? could they have been managing?
Interro-negative form
Simple form
could I not manage? could you not manage? could he not manage? could we not manage? could you not manage? could they not manage?
V-ing form
could I not be managing? could you not be managing? could he not be managing? could we not be managing? could you not be managing? could they not be managing?
Perfect
could I not have managed? could you not have managed? could he not have managed? could we not have managed? could you not have managed? could they not have managed?
V-ing perfect
could I not have been managing? could you not have been managing? could he not have been managing? could we not have been managing? could you not have been managing? could they not have been managing?