must understudy
Verbo regular: understudy - understudied- understudied

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must understudy
you must understudy
she must understudy
we must understudy
you must understudy
they must understudy 	I must be understudying
you must be understudying
she must be understudying
we must be understudying
you must be understudying
they must be understudying	I must have understudied
you must have understudied
she must have understudied
we must have understudied
you must have understudied
they must have understudied	I must have been understudying
you must have been understudying
she must have been understudying
we must have been understudying
you must have been understudying
they must have been understudying	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not understudy
you must not understudy
she must not understudy
we must not understudy
you must not understudy
they must not understudy 	I must not be understudying
you must not be understudying
she must not be understudying
we must not be understudying
you must not be understudying
they must not be understudying	I must not have understudied
you must not have understudied
she must not have understudied
we must not have understudied
you must not have understudied
they must not have understudied	I must not have been understudying
you must not have been understudying
she must not have been understudying
we must not have been understudying
you must not have been understudying
they must not have been understudying	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I understudy?
must you understudy?
must she understudy?
must we understudy?
must you understudy?
must they understudy? 	must I be understudying?
must you be understudying?
must she be understudying?
must we be understudying?
must you be understudying?
must they be understudying? 	must I have understudied?
must you have understudied?
must she have understudied?
must we have understudied?
must you have understudied?
must they have understudied? 	must I have been understudying?
must you have been understudying?
must she have been understudying?
must we have been understudying?
must you have been understudying?
must they have been understudying? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not understudy?
must you not understudy?
must she not understudy?
must we not understudy?
must you not understudy?
must they not understudy? 	must I not be understudying?
must you not be understudying?
must she not be understudying?
must we not be understudying?
must you not be understudying?
must they not be understudying? 	must I not have understudied?
must you not have understudied?
must she not have understudied?
must we not have understudied?
must you not have understudied?
must they not have understudied? 	must I not have been understudying?
must you not have been understudying?
must she not have been understudying?
must we not have been understudying?
must you not have been understudying?
must they not have been understudying?