must substitute
Verbo regular: substitute - substituted- substituted

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must substitute
you must substitute
he must substitute
we must substitute
you must substitute
they must substitute 	I must be substituting
you must be substituting
he must be substituting
we must be substituting
you must be substituting
they must be substituting	I must have substituted
you must have substituted
he must have substituted
we must have substituted
you must have substituted
they must have substituted	I must have been substituting
you must have been substituting
he must have been substituting
we must have been substituting
you must have been substituting
they must have been substituting	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't substitute
you mustn't substitute
he mustn't substitute
we mustn't substitute
you mustn't substitute
they mustn't substitute 	I mustn't be substituting
you mustn't be substituting
he mustn't be substituting
we mustn't be substituting
you mustn't be substituting
they mustn't be substituting	I mustn't have substituted
you mustn't have substituted
he mustn't have substituted
we mustn't have substituted
you mustn't have substituted
they mustn't have substituted	I mustn't have been substituting
you mustn't have been substituting
he mustn't have been substituting
we mustn't have been substituting
you mustn't have been substituting
they mustn't have been substituting	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I substitute?
must you substitute?
must he substitute?
must we substitute?
must you substitute?
must they substitute? 	must I be substituting?
must you be substituting?
must he be substituting?
must we be substituting?
must you be substituting?
must they be substituting? 	must I have substituted?
must you have substituted?
must he have substituted?
must we have substituted?
must you have substituted?
must they have substituted? 	must I have been substituting?
must you have been substituting?
must he have been substituting?
must we have been substituting?
must you have been substituting?
must they have been substituting? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I substitute?
mustn't you substitute?
mustn't he substitute?
mustn't we substitute?
mustn't you substitute?
mustn't they substitute? 	mustn't I be substituting?
mustn't you be substituting?
mustn't he be substituting?
mustn't we be substituting?
mustn't you be substituting?
mustn't they be substituting? 	mustn't I have substituted?
mustn't you have substituted?
mustn't he have substituted?
mustn't we have substituted?
mustn't you have substituted?
mustn't they have substituted? 	mustn't I have been substituting?
mustn't you have been substituting?
mustn't he have been substituting?
mustn't we have been substituting?
mustn't you have been substituting?
mustn't they have been substituting?