I could believe you could believe she could believe we could believe you could believe they could believe
V-ing form
I could be believing you could be believing she could be believing we could be believing you could be believing they could be believing
Perfect
I could have believed you could have believed she could have believed we could have believed you could have believed they could have believed
V-ing perfect
I could have been believing you could have been believing she could have been believing we could have been believing you could have been believing they could have been believing
Negation
Simple form
I could not believe you could not believe she could not believe we could not believe you could not believe they could not believe
V-ing form
I could not be believing you could not be believing she could not be believing we could not be believing you could not be believing they could not be believing
Perfect
I could not have believed you could not have believed she could not have believed we could not have believed you could not have believed they could not have believed
V-ing perfect
I could not have been believing you could not have been believing she could not have been believing we could not have been believing you could not have been believing they could not have been believing
Interrogative form
Simple form
could I believe? could you believe? could she believe? could we believe? could you believe? could they believe?
V-ing form
could I be believing? could you be believing? could she be believing? could we be believing? could you be believing? could they be believing?
Perfect
could I have believed? could you have believed? could she have believed? could we have believed? could you have believed? could they have believed?
V-ing perfect
could I have been believing? could you have been believing? could she have been believing? could we have been believing? could you have been believing? could they have been believing?
Interro-negative form
Simple form
could I not believe? could you not believe? could she not believe? could we not believe? could you not believe? could they not believe?
V-ing form
could I not be believing? could you not be believing? could she not be believing? could we not be believing? could you not be believing? could they not be believing?
Perfect
could I not have believed? could you not have believed? could she not have believed? could we not have believed? could you not have believed? could they not have believed?
V-ing perfect
could I not have been believing? could you not have been believing? could she not have been believing? could we not have been believing? could you not have been believing? could they not have been believing?