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