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