I could follow you could follow she could follow we could follow you could follow they could follow
V-ing form
I could be following you could be following she could be following we could be following you could be following they could be following
Perfect
I could have followed you could have followed she could have followed we could have followed you could have followed they could have followed
V-ing perfect
I could have been following you could have been following she could have been following we could have been following you could have been following they could have been following
Negation
Simple form
I could not follow you could not follow she could not follow we could not follow you could not follow they could not follow
V-ing form
I could not be following you could not be following she could not be following we could not be following you could not be following they could not be following
Perfect
I could not have followed you could not have followed she could not have followed we could not have followed you could not have followed they could not have followed
V-ing perfect
I could not have been following you could not have been following she could not have been following we could not have been following you could not have been following they could not have been following
Interrogative form
Simple form
could I follow? could you follow? could she follow? could we follow? could you follow? could they follow?
V-ing form
could I be following? could you be following? could she be following? could we be following? could you be following? could they be following?
Perfect
could I have followed? could you have followed? could she have followed? could we have followed? could you have followed? could they have followed?
V-ing perfect
could I have been following? could you have been following? could she have been following? could we have been following? could you have been following? could they have been following?
Interro-negative form
Simple form
could I not follow? could you not follow? could she not follow? could we not follow? could you not follow? could they not follow?
V-ing form
could I not be following? could you not be following? could she not be following? could we not be following? could you not be following? could they not be following?
Perfect
could I not have followed? could you not have followed? could she not have followed? could we not have followed? could you not have followed? could they not have followed?
V-ing perfect
could I not have been following? could you not have been following? could she not have been following? could we not have been following? could you not have been following? could they not have been following?