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