I could go you could go he could go we could go you could go they could go
V-ing form
I could be going you could be going he could be going we could be going you could be going they could be going
Perfect
I could have gone you could have gone he could have gone we could have gone you could have gone they could have gone
V-ing perfect
I could have been going you could have been going he could have been going we could have been going you could have been going they could have been going
Negation
Simple form
I could not go you could not go he could not go we could not go you could not go they could not go
V-ing form
I could not be going you could not be going he could not be going we could not be going you could not be going they could not be going
Perfect
I could not have gone you could not have gone he could not have gone we could not have gone you could not have gone they could not have gone
V-ing perfect
I could not have been going you could not have been going he could not have been going we could not have been going you could not have been going they could not have been going
Interrogative form
Simple form
could I go? could you go? could he go? could we go? could you go? could they go?
V-ing form
could I be going? could you be going? could he be going? could we be going? could you be going? could they be going?
Perfect
could I have gone? could you have gone? could he have gone? could we have gone? could you have gone? could they have gone?
V-ing perfect
could I have been going? could you have been going? could he have been going? could we have been going? could you have been going? could they have been going?
Interro-negative form
Simple form
could I not go? could you not go? could he not go? could we not go? could you not go? could they not go?
V-ing form
could I not be going? could you not be going? could he not be going? could we not be going? could you not be going? could they not be going?
Perfect
could I not have gone? could you not have gone? could he not have gone? could we not have gone? could you not have gone? could they not have gone?
V-ing perfect
could I not have been going? could you not have been going? could he not have been going? could we not have been going? could you not have been going? could they not have been going?