must undertain
Verbo regular: undertain - undertained- undertained

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must undertain
you must undertain
she must undertain
we must undertain
you must undertain
they must undertain 	I must be undertaining
you must be undertaining
she must be undertaining
we must be undertaining
you must be undertaining
they must be undertaining	I must have undertained
you must have undertained
she must have undertained
we must have undertained
you must have undertained
they must have undertained	I must have been undertaining
you must have been undertaining
she must have been undertaining
we must have been undertaining
you must have been undertaining
they must have been undertaining	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't undertain
you mustn't undertain
she mustn't undertain
we mustn't undertain
you mustn't undertain
they mustn't undertain 	I mustn't be undertaining
you mustn't be undertaining
she mustn't be undertaining
we mustn't be undertaining
you mustn't be undertaining
they mustn't be undertaining	I mustn't have undertained
you mustn't have undertained
she mustn't have undertained
we mustn't have undertained
you mustn't have undertained
they mustn't have undertained	I mustn't have been undertaining
you mustn't have been undertaining
she mustn't have been undertaining
we mustn't have been undertaining
you mustn't have been undertaining
they mustn't have been undertaining	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I undertain?
must you undertain?
must she undertain?
must we undertain?
must you undertain?
must they undertain? 	must I be undertaining?
must you be undertaining?
must she be undertaining?
must we be undertaining?
must you be undertaining?
must they be undertaining? 	must I have undertained?
must you have undertained?
must she have undertained?
must we have undertained?
must you have undertained?
must they have undertained? 	must I have been undertaining?
must you have been undertaining?
must she have been undertaining?
must we have been undertaining?
must you have been undertaining?
must they have been undertaining? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I undertain?
mustn't you undertain?
mustn't she undertain?
mustn't we undertain?
mustn't you undertain?
mustn't they undertain? 	mustn't I be undertaining?
mustn't you be undertaining?
mustn't she be undertaining?
mustn't we be undertaining?
mustn't you be undertaining?
mustn't they be undertaining? 	mustn't I have undertained?
mustn't you have undertained?
mustn't she have undertained?
mustn't we have undertained?
mustn't you have undertained?
mustn't they have undertained? 	mustn't I have been undertaining?
mustn't you have been undertaining?
mustn't she have been undertaining?
mustn't we have been undertaining?
mustn't you have been undertaining?
mustn't they have been undertaining?