must cube
Regular verb: cube - cubed- cubed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must cube
you must cube
he must cube
we must cube
you must cube
they must cube 	I must be cubing
you must be cubing
he must be cubing
we must be cubing
you must be cubing
they must be cubing	I must have cubed
you must have cubed
he must have cubed
we must have cubed
you must have cubed
they must have cubed	I must have been cubing
you must have been cubing
he must have been cubing
we must have been cubing
you must have been cubing
they must have been cubing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't cube
you mustn't cube
he mustn't cube
we mustn't cube
you mustn't cube
they mustn't cube 	I mustn't be cubing
you mustn't be cubing
he mustn't be cubing
we mustn't be cubing
you mustn't be cubing
they mustn't be cubing	I mustn't have cubed
you mustn't have cubed
he mustn't have cubed
we mustn't have cubed
you mustn't have cubed
they mustn't have cubed	I mustn't have been cubing
you mustn't have been cubing
he mustn't have been cubing
we mustn't have been cubing
you mustn't have been cubing
they mustn't have been cubing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I cube?
must you cube?
must he cube?
must we cube?
must you cube?
must they cube? 	must I be cubing?
must you be cubing?
must he be cubing?
must we be cubing?
must you be cubing?
must they be cubing? 	must I have cubed?
must you have cubed?
must he have cubed?
must we have cubed?
must you have cubed?
must they have cubed? 	must I have been cubing?
must you have been cubing?
must he have been cubing?
must we have been cubing?
must you have been cubing?
must they have been cubing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I cube?
mustn't you cube?
mustn't he cube?
mustn't we cube?
mustn't you cube?
mustn't they cube? 	mustn't I be cubing?
mustn't you be cubing?
mustn't he be cubing?
mustn't we be cubing?
mustn't you be cubing?
mustn't they be cubing? 	mustn't I have cubed?
mustn't you have cubed?
mustn't he have cubed?
mustn't we have cubed?
mustn't you have cubed?
mustn't they have cubed? 	mustn't I have been cubing?
mustn't you have been cubing?
mustn't he have been cubing?
mustn't we have been cubing?
mustn't you have been cubing?
mustn't they have been cubing?