I must goof you must goof he must goof we must goof you must goof they must goof
V-ing form
I must be goofing you must be goofing he must be goofing we must be goofing you must be goofing they must be goofing
Perfect
I must have goofed you must have goofed he must have goofed we must have goofed you must have goofed they must have goofed
V-ing perfect
I must have been goofing you must have been goofing he must have been goofing we must have been goofing you must have been goofing they must have been goofing
Negation
Simple form
I mustn't goof you mustn't goof he mustn't goof we mustn't goof you mustn't goof they mustn't goof
V-ing form
I mustn't be goofing you mustn't be goofing he mustn't be goofing we mustn't be goofing you mustn't be goofing they mustn't be goofing
Perfect
I mustn't have goofed you mustn't have goofed he mustn't have goofed we mustn't have goofed you mustn't have goofed they mustn't have goofed
V-ing perfect
I mustn't have been goofing you mustn't have been goofing he mustn't have been goofing we mustn't have been goofing you mustn't have been goofing they mustn't have been goofing
Interrogative form
Simple form
must I goof? must you goof? must he goof? must we goof? must you goof? must they goof?
V-ing form
must I be goofing? must you be goofing? must he be goofing? must we be goofing? must you be goofing? must they be goofing?
Perfect
must I have goofed? must you have goofed? must he have goofed? must we have goofed? must you have goofed? must they have goofed?
V-ing perfect
must I have been goofing? must you have been goofing? must he have been goofing? must we have been goofing? must you have been goofing? must they have been goofing?
Interro-negative form
Simple form
mustn't I goof? mustn't you goof? mustn't he goof? mustn't we goof? mustn't you goof? mustn't they goof?
V-ing form
mustn't I be goofing? mustn't you be goofing? mustn't he be goofing? mustn't we be goofing? mustn't you be goofing? mustn't they be goofing?
Perfect
mustn't I have goofed? mustn't you have goofed? mustn't he have goofed? mustn't we have goofed? mustn't you have goofed? mustn't they have goofed?
V-ing perfect
mustn't I have been goofing? mustn't you have been goofing? mustn't he have been goofing? mustn't we have been goofing? mustn't you have been goofing? mustn't they have been goofing?