I must flap you must flap she must flap we must flap you must flap they must flap
V-ing form
I must be flapping you must be flapping she must be flapping we must be flapping you must be flapping they must be flapping
Perfect
I must have flapped you must have flapped she must have flapped we must have flapped you must have flapped they must have flapped
V-ing perfect
I must have been flapping you must have been flapping she must have been flapping we must have been flapping you must have been flapping they must have been flapping
Negation
Simple form
I must not flap you must not flap she must not flap we must not flap you must not flap they must not flap
V-ing form
I must not be flapping you must not be flapping she must not be flapping we must not be flapping you must not be flapping they must not be flapping
Perfect
I must not have flapped you must not have flapped she must not have flapped we must not have flapped you must not have flapped they must not have flapped
V-ing perfect
I must not have been flapping you must not have been flapping she must not have been flapping we must not have been flapping you must not have been flapping they must not have been flapping
Interrogative form
Simple form
must I flap? must you flap? must she flap? must we flap? must you flap? must they flap?
V-ing form
must I be flapping? must you be flapping? must she be flapping? must we be flapping? must you be flapping? must they be flapping?
Perfect
must I have flapped? must you have flapped? must she have flapped? must we have flapped? must you have flapped? must they have flapped?
V-ing perfect
must I have been flapping? must you have been flapping? must she have been flapping? must we have been flapping? must you have been flapping? must they have been flapping?
Interro-negative form
Simple form
must I not flap? must you not flap? must she not flap? must we not flap? must you not flap? must they not flap?
V-ing form
must I not be flapping? must you not be flapping? must she not be flapping? must we not be flapping? must you not be flapping? must they not be flapping?
Perfect
must I not have flapped? must you not have flapped? must she not have flapped? must we not have flapped? must you not have flapped? must they not have flapped?
V-ing perfect
must I not have been flapping? must you not have been flapping? must she not have been flapping? must we not have been flapping? must you not have been flapping? must they not have been flapping?