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