I could flicker you could flicker he could flicker we could flicker you could flicker they could flicker
V-ing form
I could be flickering you could be flickering he could be flickering we could be flickering you could be flickering they could be flickering
Perfect
I could have flickered you could have flickered he could have flickered we could have flickered you could have flickered they could have flickered
V-ing perfect
I could have been flickering you could have been flickering he could have been flickering we could have been flickering you could have been flickering they could have been flickering
Negation
Simple form
I could not flicker you could not flicker he could not flicker we could not flicker you could not flicker they could not flicker
V-ing form
I could not be flickering you could not be flickering he could not be flickering we could not be flickering you could not be flickering they could not be flickering
Perfect
I could not have flickered you could not have flickered he could not have flickered we could not have flickered you could not have flickered they could not have flickered
V-ing perfect
I could not have been flickering you could not have been flickering he could not have been flickering we could not have been flickering you could not have been flickering they could not have been flickering
Interrogative form
Simple form
could I flicker? could you flicker? could he flicker? could we flicker? could you flicker? could they flicker?
V-ing form
could I be flickering? could you be flickering? could he be flickering? could we be flickering? could you be flickering? could they be flickering?
Perfect
could I have flickered? could you have flickered? could he have flickered? could we have flickered? could you have flickered? could they have flickered?
V-ing perfect
could I have been flickering? could you have been flickering? could he have been flickering? could we have been flickering? could you have been flickering? could they have been flickering?
Interro-negative form
Simple form
could I not flicker? could you not flicker? could he not flicker? could we not flicker? could you not flicker? could they not flicker?
V-ing form
could I not be flickering? could you not be flickering? could he not be flickering? could we not be flickering? could you not be flickering? could they not be flickering?
Perfect
could I not have flickered? could you not have flickered? could he not have flickered? could we not have flickered? could you not have flickered? could they not have flickered?
V-ing perfect
could I not have been flickering? could you not have been flickering? could he not have been flickering? could we not have been flickering? could you not have been flickering? could they not have been flickering?