I can author you can author she can author we can author you can author they can author
V-ing form
I can be authoring you can be authoring she can be authoring we can be authoring you can be authoring they can be authoring
Perfect
I can have authored you can have authored she can have authored we can have authored you can have authored they can have authored
V-ing perfect
I can have been authoring you can have been authoring she can have been authoring we can have been authoring you can have been authoring they can have been authoring
Negation
Simple form
I can't author you can't author she can't author we can't author you can't author they can't author
V-ing form
I can't be authoring you can't be authoring she can't be authoring we can't be authoring you can't be authoring they can't be authoring
Perfect
I can't have authored you can't have authored she can't have authored we can't have authored you can't have authored they can't have authored
V-ing perfect
I can't have been authoring you can't have been authoring she can't have been authoring we can't have been authoring you can't have been authoring they can't have been authoring
Interrogative form
Simple form
can I author? can you author? can she author? can we author? can you author? can they author?
V-ing form
can I be authoring? can you be authoring? can she be authoring? can we be authoring? can you be authoring? can they be authoring?
Perfect
can I have authored? can you have authored? can she have authored? can we have authored? can you have authored? can they have authored?
V-ing perfect
can I have been authoring? can you have been authoring? can she have been authoring? can we have been authoring? can you have been authoring? can they have been authoring?
Interro-negative form
Simple form
can't I author? can't you author? can't she author? can't we author? can't you author? can't they author?
V-ing form
can't I be authoring? can't you be authoring? can't she be authoring? can't we be authoring? can't you be authoring? can't they be authoring?
Perfect
can't I have authored? can't you have authored? can't she have authored? can't we have authored? can't you have authored? can't they have authored?
V-ing perfect
can't I have been authoring? can't you have been authoring? can't she have been authoring? can't we have been authoring? can't you have been authoring? can't they have been authoring?