must frown
Regular verb: frown - frowned- frowned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must frown
you must frown
he must frown
we must frown
you must frown
they must frown 	I must be frowning
you must be frowning
he must be frowning
we must be frowning
you must be frowning
they must be frowning	I must have frowned
you must have frowned
he must have frowned
we must have frowned
you must have frowned
they must have frowned	I must have been frowning
you must have been frowning
he must have been frowning
we must have been frowning
you must have been frowning
they must have been frowning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not frown
you must not frown
he must not frown
we must not frown
you must not frown
they must not frown 	I must not be frowning
you must not be frowning
he must not be frowning
we must not be frowning
you must not be frowning
they must not be frowning	I must not have frowned
you must not have frowned
he must not have frowned
we must not have frowned
you must not have frowned
they must not have frowned	I must not have been frowning
you must not have been frowning
he must not have been frowning
we must not have been frowning
you must not have been frowning
they must not have been frowning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I frown?
must you frown?
must he frown?
must we frown?
must you frown?
must they frown? 	must I be frowning?
must you be frowning?
must he be frowning?
must we be frowning?
must you be frowning?
must they be frowning? 	must I have frowned?
must you have frowned?
must he have frowned?
must we have frowned?
must you have frowned?
must they have frowned? 	must I have been frowning?
must you have been frowning?
must he have been frowning?
must we have been frowning?
must you have been frowning?
must they have been frowning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not frown?
must you not frown?
must he not frown?
must we not frown?
must you not frown?
must they not frown? 	must I not be frowning?
must you not be frowning?
must he not be frowning?
must we not be frowning?
must you not be frowning?
must they not be frowning? 	must I not have frowned?
must you not have frowned?
must he not have frowned?
must we not have frowned?
must you not have frowned?
must they not have frowned? 	must I not have been frowning?
must you not have been frowning?
must he not have been frowning?
must we not have been frowning?
must you not have been frowning?
must they not have been frowning?