must birl
Regular verb: birl - birled- birled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must birl
you must birl
she must birl
we must birl
you must birl
they must birl 	I must be birling
you must be birling
she must be birling
we must be birling
you must be birling
they must be birling	I must have birled
you must have birled
she must have birled
we must have birled
you must have birled
they must have birled	I must have been birling
you must have been birling
she must have been birling
we must have been birling
you must have been birling
they must have been birling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't birl
you mustn't birl
she mustn't birl
we mustn't birl
you mustn't birl
they mustn't birl 	I mustn't be birling
you mustn't be birling
she mustn't be birling
we mustn't be birling
you mustn't be birling
they mustn't be birling	I mustn't have birled
you mustn't have birled
she mustn't have birled
we mustn't have birled
you mustn't have birled
they mustn't have birled	I mustn't have been birling
you mustn't have been birling
she mustn't have been birling
we mustn't have been birling
you mustn't have been birling
they mustn't have been birling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I birl?
must you birl?
must she birl?
must we birl?
must you birl?
must they birl? 	must I be birling?
must you be birling?
must she be birling?
must we be birling?
must you be birling?
must they be birling? 	must I have birled?
must you have birled?
must she have birled?
must we have birled?
must you have birled?
must they have birled? 	must I have been birling?
must you have been birling?
must she have been birling?
must we have been birling?
must you have been birling?
must they have been birling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I birl?
mustn't you birl?
mustn't she birl?
mustn't we birl?
mustn't you birl?
mustn't they birl? 	mustn't I be birling?
mustn't you be birling?
mustn't she be birling?
mustn't we be birling?
mustn't you be birling?
mustn't they be birling? 	mustn't I have birled?
mustn't you have birled?
mustn't she have birled?
mustn't we have birled?
mustn't you have birled?
mustn't they have birled? 	mustn't I have been birling?
mustn't you have been birling?
mustn't she have been birling?
mustn't we have been birling?
mustn't you have been birling?
mustn't they have been birling?