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