must chair
Regular verb: chair - chaired- chaired

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must chair
you must chair
he must chair
we must chair
you must chair
they must chair 	I must be chairing
you must be chairing
he must be chairing
we must be chairing
you must be chairing
they must be chairing	I must have chaired
you must have chaired
he must have chaired
we must have chaired
you must have chaired
they must have chaired	I must have been chairing
you must have been chairing
he must have been chairing
we must have been chairing
you must have been chairing
they must have been chairing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't chair
you mustn't chair
he mustn't chair
we mustn't chair
you mustn't chair
they mustn't chair 	I mustn't be chairing
you mustn't be chairing
he mustn't be chairing
we mustn't be chairing
you mustn't be chairing
they mustn't be chairing	I mustn't have chaired
you mustn't have chaired
he mustn't have chaired
we mustn't have chaired
you mustn't have chaired
they mustn't have chaired	I mustn't have been chairing
you mustn't have been chairing
he mustn't have been chairing
we mustn't have been chairing
you mustn't have been chairing
they mustn't have been chairing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I chair?
must you chair?
must he chair?
must we chair?
must you chair?
must they chair? 	must I be chairing?
must you be chairing?
must he be chairing?
must we be chairing?
must you be chairing?
must they be chairing? 	must I have chaired?
must you have chaired?
must he have chaired?
must we have chaired?
must you have chaired?
must they have chaired? 	must I have been chairing?
must you have been chairing?
must he have been chairing?
must we have been chairing?
must you have been chairing?
must they have been chairing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I chair?
mustn't you chair?
mustn't he chair?
mustn't we chair?
mustn't you chair?
mustn't they chair? 	mustn't I be chairing?
mustn't you be chairing?
mustn't he be chairing?
mustn't we be chairing?
mustn't you be chairing?
mustn't they be chairing? 	mustn't I have chaired?
mustn't you have chaired?
mustn't he have chaired?
mustn't we have chaired?
mustn't you have chaired?
mustn't they have chaired? 	mustn't I have been chairing?
mustn't you have been chairing?
mustn't he have been chairing?
mustn't we have been chairing?
mustn't you have been chairing?
mustn't they have been chairing?