must understudy
Verbo regular: understudy - understudied- understudied

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must understudy
you must understudy
he must understudy
we must understudy
you must understudy
they must understudy 	I must be understudying
you must be understudying
he must be understudying
we must be understudying
you must be understudying
they must be understudying	I must have understudied
you must have understudied
he 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
he must have been understudying
we must have been understudying
you must have been understudying
they must have been understudying	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't understudy
you mustn't understudy
he mustn't understudy
we mustn't understudy
you mustn't understudy
they mustn't understudy 	I mustn't be understudying
you mustn't be understudying
he mustn't be understudying
we mustn't be understudying
you mustn't be understudying
they mustn't be understudying	I mustn't have understudied
you mustn't have understudied
he mustn't have understudied
we mustn't have understudied
you mustn't have understudied
they mustn't have understudied	I mustn't have been understudying
you mustn't have been understudying
he mustn't have been understudying
we mustn't have been understudying
you mustn't have been understudying
they mustn't have been understudying	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I understudy?
must you understudy?
must he understudy?
must we understudy?
must you understudy?
must they understudy? 	must I be understudying?
must you be understudying?
must he be understudying?
must we be understudying?
must you be understudying?
must they be understudying? 	must I have understudied?
must you have understudied?
must he 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 he have been understudying?
must we have been understudying?
must you have been understudying?
must they have been understudying? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I understudy?
mustn't you understudy?
mustn't he understudy?
mustn't we understudy?
mustn't you understudy?
mustn't they understudy? 	mustn't I be understudying?
mustn't you be understudying?
mustn't he be understudying?
mustn't we be understudying?
mustn't you be understudying?
mustn't they be understudying? 	mustn't I have understudied?
mustn't you have understudied?
mustn't he have understudied?
mustn't we have understudied?
mustn't you have understudied?
mustn't they have understudied? 	mustn't I have been understudying?
mustn't you have been understudying?
mustn't he have been understudying?
mustn't we have been understudying?
mustn't you have been understudying?
mustn't they have been understudying?