I could look you could look he could look we could look you could look they could look
V-ing form
I could be looking you could be looking he could be looking we could be looking you could be looking they could be looking
Perfect
I could have looked you could have looked he could have looked we could have looked you could have looked they could have looked
V-ing perfect
I could have been looking you could have been looking he could have been looking we could have been looking you could have been looking they could have been looking
Negation
Simple form
I could not look you could not look he could not look we could not look you could not look they could not look
V-ing form
I could not be looking you could not be looking he could not be looking we could not be looking you could not be looking they could not be looking
Perfect
I could not have looked you could not have looked he could not have looked we could not have looked you could not have looked they could not have looked
V-ing perfect
I could not have been looking you could not have been looking he could not have been looking we could not have been looking you could not have been looking they could not have been looking
Interrogative form
Simple form
could I look? could you look? could he look? could we look? could you look? could they look?
V-ing form
could I be looking? could you be looking? could he be looking? could we be looking? could you be looking? could they be looking?
Perfect
could I have looked? could you have looked? could he have looked? could we have looked? could you have looked? could they have looked?
V-ing perfect
could I have been looking? could you have been looking? could he have been looking? could we have been looking? could you have been looking? could they have been looking?
Interro-negative form
Simple form
could I not look? could you not look? could he not look? could we not look? could you not look? could they not look?
V-ing form
could I not be looking? could you not be looking? could he not be looking? could we not be looking? could you not be looking? could they not be looking?
Perfect
could I not have looked? could you not have looked? could he not have looked? could we not have looked? could you not have looked? could they not have looked?
V-ing perfect
could I not have been looking? could you not have been looking? could he not have been looking? could we not have been looking? could you not have been looking? could they not have been looking?