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