English verb conjugation
MUST UNDERSTUDY

Regular verb: understudy - understudied - understudied

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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

Negation

Simple form	V-ing form
I mustn't understudy you mustn't understudy she 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 she 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 she 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 she 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 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?
Perfect	V-ing perfect
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?

Interro-negative form

Simple form	V-ing form
mustn't I understudy? mustn't you understudy? mustn't she 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 she 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 she 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 she have been understudying? mustn't we have been understudying? mustn't you have been understudying? mustn't they have been understudying?