must counterbalance
Regular verb: counterbalance - counterbalanced- counterbalanced

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must counterbalance
you must counterbalance
he must counterbalance
we must counterbalance
you must counterbalance
they must counterbalance 	I must be counterbalancing
you must be counterbalancing
he must be counterbalancing
we must be counterbalancing
you must be counterbalancing
they must be counterbalancing	I must have counterbalanced
you must have counterbalanced
he must have counterbalanced
we must have counterbalanced
you must have counterbalanced
they must have counterbalanced	I must have been counterbalancing
you must have been counterbalancing
he must have been counterbalancing
we must have been counterbalancing
you must have been counterbalancing
they must have been counterbalancing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't counterbalance
you mustn't counterbalance
he mustn't counterbalance
we mustn't counterbalance
you mustn't counterbalance
they mustn't counterbalance 	I mustn't be counterbalancing
you mustn't be counterbalancing
he mustn't be counterbalancing
we mustn't be counterbalancing
you mustn't be counterbalancing
they mustn't be counterbalancing	I mustn't have counterbalanced
you mustn't have counterbalanced
he mustn't have counterbalanced
we mustn't have counterbalanced
you mustn't have counterbalanced
they mustn't have counterbalanced	I mustn't have been counterbalancing
you mustn't have been counterbalancing
he mustn't have been counterbalancing
we mustn't have been counterbalancing
you mustn't have been counterbalancing
they mustn't have been counterbalancing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I counterbalance?
must you counterbalance?
must he counterbalance?
must we counterbalance?
must you counterbalance?
must they counterbalance? 	must I be counterbalancing?
must you be counterbalancing?
must he be counterbalancing?
must we be counterbalancing?
must you be counterbalancing?
must they be counterbalancing? 	must I have counterbalanced?
must you have counterbalanced?
must he have counterbalanced?
must we have counterbalanced?
must you have counterbalanced?
must they have counterbalanced? 	must I have been counterbalancing?
must you have been counterbalancing?
must he have been counterbalancing?
must we have been counterbalancing?
must you have been counterbalancing?
must they have been counterbalancing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I counterbalance?
mustn't you counterbalance?
mustn't he counterbalance?
mustn't we counterbalance?
mustn't you counterbalance?
mustn't they counterbalance? 	mustn't I be counterbalancing?
mustn't you be counterbalancing?
mustn't he be counterbalancing?
mustn't we be counterbalancing?
mustn't you be counterbalancing?
mustn't they be counterbalancing? 	mustn't I have counterbalanced?
mustn't you have counterbalanced?
mustn't he have counterbalanced?
mustn't we have counterbalanced?
mustn't you have counterbalanced?
mustn't they have counterbalanced? 	mustn't I have been counterbalancing?
mustn't you have been counterbalancing?
mustn't he have been counterbalancing?
mustn't we have been counterbalancing?
mustn't you have been counterbalancing?
mustn't they have been counterbalancing?