I could author you could author she could author we could author you could author they could author
V-ing form
I could be authoring you could be authoring she could be authoring we could be authoring you could be authoring they could be authoring
Perfect
I could have authored you could have authored she 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 she 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 she 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 she 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 she 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 she 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 she author? could we author? could you author? could they author?
V-ing form
could I be authoring? could you be authoring? could she be authoring? could we be authoring? could you be authoring? could they be authoring?
Perfect
could I have authored? could you have authored? could she 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 she 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 she 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 she 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 she 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 she not have been authoring? could we not have been authoring? could you not have been authoring? could they not have been authoring?