English verb conjugation
MUST UNDERSTUDY

Regular verb: understudy - understudied - understudied

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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

Negation

Simple form	V-ing form
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
Perfect	V-ing perfect
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

Interrogative form

Simple form	V-ing form
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?
Perfect	V-ing perfect
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?

Interro-negative form

Simple form	V-ing form
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?
Perfect	V-ing perfect
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?