I must breathe you must breathe she must breathe we must breathe you must breathe they must breathe
V-ing form
I must be breathing you must be breathing she must be breathing we must be breathing you must be breathing they must be breathing
Perfect
I must have breathed you must have breathed she must have breathed we must have breathed you must have breathed they must have breathed
V-ing perfect
I must have been breathing you must have been breathing she must have been breathing we must have been breathing you must have been breathing they must have been breathing
Negation
Simple form
I mustn't breathe you mustn't breathe she mustn't breathe we mustn't breathe you mustn't breathe they mustn't breathe
V-ing form
I mustn't be breathing you mustn't be breathing she mustn't be breathing we mustn't be breathing you mustn't be breathing they mustn't be breathing
Perfect
I mustn't have breathed you mustn't have breathed she mustn't have breathed we mustn't have breathed you mustn't have breathed they mustn't have breathed
V-ing perfect
I mustn't have been breathing you mustn't have been breathing she mustn't have been breathing we mustn't have been breathing you mustn't have been breathing they mustn't have been breathing
Interrogative form
Simple form
must I breathe? must you breathe? must she breathe? must we breathe? must you breathe? must they breathe?
V-ing form
must I be breathing? must you be breathing? must she be breathing? must we be breathing? must you be breathing? must they be breathing?
Perfect
must I have breathed? must you have breathed? must she have breathed? must we have breathed? must you have breathed? must they have breathed?
V-ing perfect
must I have been breathing? must you have been breathing? must she have been breathing? must we have been breathing? must you have been breathing? must they have been breathing?
Interro-negative form
Simple form
mustn't I breathe? mustn't you breathe? mustn't she breathe? mustn't we breathe? mustn't you breathe? mustn't they breathe?
V-ing form
mustn't I be breathing? mustn't you be breathing? mustn't she be breathing? mustn't we be breathing? mustn't you be breathing? mustn't they be breathing?
Perfect
mustn't I have breathed? mustn't you have breathed? mustn't she have breathed? mustn't we have breathed? mustn't you have breathed? mustn't they have breathed?
V-ing perfect
mustn't I have been breathing? mustn't you have been breathing? mustn't she have been breathing? mustn't we have been breathing? mustn't you have been breathing? mustn't they have been breathing?