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