I could author you could author he could author we could author you could author they could author
V-ing form
I could be authoring you could be authoring he could be authoring we could be authoring you could be authoring they could be authoring
Perfect
I could have authored you could have authored he could have authored we could have authored you could have authored they could have authored
V-ing perfect
I could have been authoring you could have been authoring he could have been authoring we could have been authoring you could have been authoring they could have been authoring
Negation
Simple form
I could not author you could not author he could not author we could not author you could not author they could not author
V-ing form
I could not be authoring you could not be authoring he could not be authoring we could not be authoring you could not be authoring they could not be authoring
Perfect
I could not have authored you could not have authored he could not have authored we could not have authored you could not have authored they could not have authored
V-ing perfect
I could not have been authoring you could not have been authoring he could not have been authoring we could not have been authoring you could not have been authoring they could not have been authoring
Interrogative form
Simple form
could I author? could you author? could he author? could we author? could you author? could they author?
V-ing form
could I be authoring? could you be authoring? could he be authoring? could we be authoring? could you be authoring? could they be authoring?
Perfect
could I have authored? could you have authored? could he have authored? could we have authored? could you have authored? could they have authored?
V-ing perfect
could I have been authoring? could you have been authoring? could he have been authoring? could we have been authoring? could you have been authoring? could they have been authoring?
Interro-negative form
Simple form
could I not author? could you not author? could he not author? could we not author? could you not author? could they not author?
V-ing form
could I not be authoring? could you not be authoring? could he not be authoring? could we not be authoring? could you not be authoring? could they not be authoring?
Perfect
could I not have authored? could you not have authored? could he not have authored? could we not have authored? could you not have authored? could they not have authored?
V-ing perfect
could I not have been authoring? could you not have been authoring? could he not have been authoring? could we not have been authoring? could you not have been authoring? could they not have been authoring?