must master
Verbo regular: master - mastered- mastered

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must master
you must master
he must master
we must master
you must master
they must master 	I must be mastering
you must be mastering
he must be mastering
we must be mastering
you must be mastering
they must be mastering	I must have mastered
you must have mastered
he must have mastered
we must have mastered
you must have mastered
they must have mastered	I must have been mastering
you must have been mastering
he must have been mastering
we must have been mastering
you must have been mastering
they must have been mastering	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not master
you must not master
he must not master
we must not master
you must not master
they must not master 	I must not be mastering
you must not be mastering
he must not be mastering
we must not be mastering
you must not be mastering
they must not be mastering	I must not have mastered
you must not have mastered
he must not have mastered
we must not have mastered
you must not have mastered
they must not have mastered	I must not have been mastering
you must not have been mastering
he must not have been mastering
we must not have been mastering
you must not have been mastering
they must not have been mastering	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I master?
must you master?
must he master?
must we master?
must you master?
must they master? 	must I be mastering?
must you be mastering?
must he be mastering?
must we be mastering?
must you be mastering?
must they be mastering? 	must I have mastered?
must you have mastered?
must he have mastered?
must we have mastered?
must you have mastered?
must they have mastered? 	must I have been mastering?
must you have been mastering?
must he have been mastering?
must we have been mastering?
must you have been mastering?
must they have been mastering? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not master?
must you not master?
must he not master?
must we not master?
must you not master?
must they not master? 	must I not be mastering?
must you not be mastering?
must he not be mastering?
must we not be mastering?
must you not be mastering?
must they not be mastering? 	must I not have mastered?
must you not have mastered?
must he not have mastered?
must we not have mastered?
must you not have mastered?
must they not have mastered? 	must I not have been mastering?
must you not have been mastering?
must he not have been mastering?
must we not have been mastering?
must you not have been mastering?
must they not have been mastering?