must underperform
Regular verb: underperform - underperformed- underperformed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must underperform
you must underperform
he must underperform
we must underperform
you must underperform
they must underperform 	I must be underperforming
you must be underperforming
he must be underperforming
we must be underperforming
you must be underperforming
they must be underperforming	I must have underperformed
you must have underperformed
he must have underperformed
we must have underperformed
you must have underperformed
they must have underperformed	I must have been underperforming
you must have been underperforming
he must have been underperforming
we must have been underperforming
you must have been underperforming
they must have been underperforming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't underperform
you mustn't underperform
he mustn't underperform
we mustn't underperform
you mustn't underperform
they mustn't underperform 	I mustn't be underperforming
you mustn't be underperforming
he mustn't be underperforming
we mustn't be underperforming
you mustn't be underperforming
they mustn't be underperforming	I mustn't have underperformed
you mustn't have underperformed
he mustn't have underperformed
we mustn't have underperformed
you mustn't have underperformed
they mustn't have underperformed	I mustn't have been underperforming
you mustn't have been underperforming
he mustn't have been underperforming
we mustn't have been underperforming
you mustn't have been underperforming
they mustn't have been underperforming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I underperform?
must you underperform?
must he underperform?
must we underperform?
must you underperform?
must they underperform? 	must I be underperforming?
must you be underperforming?
must he be underperforming?
must we be underperforming?
must you be underperforming?
must they be underperforming? 	must I have underperformed?
must you have underperformed?
must he have underperformed?
must we have underperformed?
must you have underperformed?
must they have underperformed? 	must I have been underperforming?
must you have been underperforming?
must he have been underperforming?
must we have been underperforming?
must you have been underperforming?
must they have been underperforming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I underperform?
mustn't you underperform?
mustn't he underperform?
mustn't we underperform?
mustn't you underperform?
mustn't they underperform? 	mustn't I be underperforming?
mustn't you be underperforming?
mustn't he be underperforming?
mustn't we be underperforming?
mustn't you be underperforming?
mustn't they be underperforming? 	mustn't I have underperformed?
mustn't you have underperformed?
mustn't he have underperformed?
mustn't we have underperformed?
mustn't you have underperformed?
mustn't they have underperformed? 	mustn't I have been underperforming?
mustn't you have been underperforming?
mustn't he have been underperforming?
mustn't we have been underperforming?
mustn't you have been underperforming?
mustn't they have been underperforming?