must jib
Regular verb: jib - jibbed- jibbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must jib
you must jib
he must jib
we must jib
you must jib
they must jib 	I must be jibbing
you must be jibbing
he must be jibbing
we must be jibbing
you must be jibbing
they must be jibbing	I must have jibbed
you must have jibbed
he must have jibbed
we must have jibbed
you must have jibbed
they must have jibbed	I must have been jibbing
you must have been jibbing
he must have been jibbing
we must have been jibbing
you must have been jibbing
they must have been jibbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't jib
you mustn't jib
he mustn't jib
we mustn't jib
you mustn't jib
they mustn't jib 	I mustn't be jibbing
you mustn't be jibbing
he mustn't be jibbing
we mustn't be jibbing
you mustn't be jibbing
they mustn't be jibbing	I mustn't have jibbed
you mustn't have jibbed
he mustn't have jibbed
we mustn't have jibbed
you mustn't have jibbed
they mustn't have jibbed	I mustn't have been jibbing
you mustn't have been jibbing
he mustn't have been jibbing
we mustn't have been jibbing
you mustn't have been jibbing
they mustn't have been jibbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I jib?
must you jib?
must he jib?
must we jib?
must you jib?
must they jib? 	must I be jibbing?
must you be jibbing?
must he be jibbing?
must we be jibbing?
must you be jibbing?
must they be jibbing? 	must I have jibbed?
must you have jibbed?
must he have jibbed?
must we have jibbed?
must you have jibbed?
must they have jibbed? 	must I have been jibbing?
must you have been jibbing?
must he have been jibbing?
must we have been jibbing?
must you have been jibbing?
must they have been jibbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I jib?
mustn't you jib?
mustn't he jib?
mustn't we jib?
mustn't you jib?
mustn't they jib? 	mustn't I be jibbing?
mustn't you be jibbing?
mustn't he be jibbing?
mustn't we be jibbing?
mustn't you be jibbing?
mustn't they be jibbing? 	mustn't I have jibbed?
mustn't you have jibbed?
mustn't he have jibbed?
mustn't we have jibbed?
mustn't you have jibbed?
mustn't they have jibbed? 	mustn't I have been jibbing?
mustn't you have been jibbing?
mustn't he have been jibbing?
mustn't we have been jibbing?
mustn't you have been jibbing?
mustn't they have been jibbing?