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