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