must scowl
Regular verb: scowl - scowled- scowled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must scowl
you must scowl
he must scowl
we must scowl
you must scowl
they must scowl 	I must be scowling
you must be scowling
he must be scowling
we must be scowling
you must be scowling
they must be scowling	I must have scowled
you must have scowled
he must have scowled
we must have scowled
you must have scowled
they must have scowled	I must have been scowling
you must have been scowling
he must have been scowling
we must have been scowling
you must have been scowling
they must have been scowling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't scowl
you mustn't scowl
he mustn't scowl
we mustn't scowl
you mustn't scowl
they mustn't scowl 	I mustn't be scowling
you mustn't be scowling
he mustn't be scowling
we mustn't be scowling
you mustn't be scowling
they mustn't be scowling	I mustn't have scowled
you mustn't have scowled
he mustn't have scowled
we mustn't have scowled
you mustn't have scowled
they mustn't have scowled	I mustn't have been scowling
you mustn't have been scowling
he mustn't have been scowling
we mustn't have been scowling
you mustn't have been scowling
they mustn't have been scowling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I scowl?
must you scowl?
must he scowl?
must we scowl?
must you scowl?
must they scowl? 	must I be scowling?
must you be scowling?
must he be scowling?
must we be scowling?
must you be scowling?
must they be scowling? 	must I have scowled?
must you have scowled?
must he have scowled?
must we have scowled?
must you have scowled?
must they have scowled? 	must I have been scowling?
must you have been scowling?
must he have been scowling?
must we have been scowling?
must you have been scowling?
must they have been scowling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I scowl?
mustn't you scowl?
mustn't he scowl?
mustn't we scowl?
mustn't you scowl?
mustn't they scowl? 	mustn't I be scowling?
mustn't you be scowling?
mustn't he be scowling?
mustn't we be scowling?
mustn't you be scowling?
mustn't they be scowling? 	mustn't I have scowled?
mustn't you have scowled?
mustn't he have scowled?
mustn't we have scowled?
mustn't you have scowled?
mustn't they have scowled? 	mustn't I have been scowling?
mustn't you have been scowling?
mustn't he have been scowling?
mustn't we have been scowling?
mustn't you have been scowling?
mustn't they have been scowling?