I must flutter you must flutter she must flutter we must flutter you must flutter they must flutter
V-ing form
I must be fluttering you must be fluttering she must be fluttering we must be fluttering you must be fluttering they must be fluttering
Perfect
I must have fluttered you must have fluttered she 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 she 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 she 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 she 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 she 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 she 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 she flutter? must we flutter? must you flutter? must they flutter?
V-ing form
must I be fluttering? must you be fluttering? must she be fluttering? must we be fluttering? must you be fluttering? must they be fluttering?
Perfect
must I have fluttered? must you have fluttered? must she 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 she 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 she 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 she 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 she 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 she have been fluttering? mustn't we have been fluttering? mustn't you have been fluttering? mustn't they have been fluttering?