I could manage you could manage she could manage we could manage you could manage they could manage
V-ing form
I could be managing you could be managing she could be managing we could be managing you could be managing they could be managing
Perfect
I could have managed you could have managed she 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 she could have been managing we could have been managing you could have been managing they could have been managing
Negation
Simple form
I couldn't manage you couldn't manage she couldn't manage we couldn't manage you couldn't manage they couldn't manage
V-ing form
I couldn't be managing you couldn't be managing she couldn't be managing we couldn't be managing you couldn't be managing they couldn't be managing
Perfect
I couldn't have managed you couldn't have managed she couldn't have managed we couldn't have managed you couldn't have managed they couldn't have managed
V-ing perfect
I couldn't have been managing you couldn't have been managing she couldn't have been managing we couldn't have been managing you couldn't have been managing they couldn't have been managing
Interrogative form
Simple form
could I manage? could you manage? could she manage? could we manage? could you manage? could they manage?
V-ing form
could I be managing? could you be managing? could she be managing? could we be managing? could you be managing? could they be managing?
Perfect
could I have managed? could you have managed? could she 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 she have been managing? could we have been managing? could you have been managing? could they have been managing?
Interro-negative form
Simple form
couldn't I manage? couldn't you manage? couldn't she manage? couldn't we manage? couldn't you manage? couldn't they manage?
V-ing form
couldn't I be managing? couldn't you be managing? couldn't she be managing? couldn't we be managing? couldn't you be managing? couldn't they be managing?
Perfect
couldn't I have managed? couldn't you have managed? couldn't she have managed? couldn't we have managed? couldn't you have managed? couldn't they have managed?
V-ing perfect
couldn't I have been managing? couldn't you have been managing? couldn't she have been managing? couldn't we have been managing? couldn't you have been managing? couldn't they have been managing?