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