must flabbergast
Regular verb: flabbergast - flabbergasted- flabbergasted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must flabbergast
you must flabbergast
he must flabbergast
we must flabbergast
you must flabbergast
they must flabbergast 	I must be flabbergasting
you must be flabbergasting
he must be flabbergasting
we must be flabbergasting
you must be flabbergasting
they must be flabbergasting	I must have flabbergasted
you must have flabbergasted
he must have flabbergasted
we must have flabbergasted
you must have flabbergasted
they must have flabbergasted	I must have been flabbergasting
you must have been flabbergasting
he must have been flabbergasting
we must have been flabbergasting
you must have been flabbergasting
they must have been flabbergasting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't flabbergast
you mustn't flabbergast
he mustn't flabbergast
we mustn't flabbergast
you mustn't flabbergast
they mustn't flabbergast 	I mustn't be flabbergasting
you mustn't be flabbergasting
he mustn't be flabbergasting
we mustn't be flabbergasting
you mustn't be flabbergasting
they mustn't be flabbergasting	I mustn't have flabbergasted
you mustn't have flabbergasted
he mustn't have flabbergasted
we mustn't have flabbergasted
you mustn't have flabbergasted
they mustn't have flabbergasted	I mustn't have been flabbergasting
you mustn't have been flabbergasting
he mustn't have been flabbergasting
we mustn't have been flabbergasting
you mustn't have been flabbergasting
they mustn't have been flabbergasting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I flabbergast?
must you flabbergast?
must he flabbergast?
must we flabbergast?
must you flabbergast?
must they flabbergast? 	must I be flabbergasting?
must you be flabbergasting?
must he be flabbergasting?
must we be flabbergasting?
must you be flabbergasting?
must they be flabbergasting? 	must I have flabbergasted?
must you have flabbergasted?
must he have flabbergasted?
must we have flabbergasted?
must you have flabbergasted?
must they have flabbergasted? 	must I have been flabbergasting?
must you have been flabbergasting?
must he have been flabbergasting?
must we have been flabbergasting?
must you have been flabbergasting?
must they have been flabbergasting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I flabbergast?
mustn't you flabbergast?
mustn't he flabbergast?
mustn't we flabbergast?
mustn't you flabbergast?
mustn't they flabbergast? 	mustn't I be flabbergasting?
mustn't you be flabbergasting?
mustn't he be flabbergasting?
mustn't we be flabbergasting?
mustn't you be flabbergasting?
mustn't they be flabbergasting? 	mustn't I have flabbergasted?
mustn't you have flabbergasted?
mustn't he have flabbergasted?
mustn't we have flabbergasted?
mustn't you have flabbergasted?
mustn't they have flabbergasted? 	mustn't I have been flabbergasting?
mustn't you have been flabbergasting?
mustn't he have been flabbergasting?
mustn't we have been flabbergasting?
mustn't you have been flabbergasting?
mustn't they have been flabbergasting?