English verb conjugation
MUST FLATTEN

Regular verb: flatten - flattened - flattened

Affirmation

Simple form	V-ing form
I must flatten you must flatten he must flatten we must flatten you must flatten they must flatten	I must be flattening you must be flattening he must be flattening we must be flattening you must be flattening they must be flattening
Perfect	V-ing perfect
I must have flattened you must have flattened he must have flattened we must have flattened you must have flattened they must have flattened	I must have been flattening you must have been flattening he must have been flattening we must have been flattening you must have been flattening they must have been flattening

Negation

Simple form	V-ing form
I mustn't flatten you mustn't flatten he mustn't flatten we mustn't flatten you mustn't flatten they mustn't flatten	I mustn't be flattening you mustn't be flattening he mustn't be flattening we mustn't be flattening you mustn't be flattening they mustn't be flattening
Perfect	V-ing perfect
I mustn't have flattened you mustn't have flattened he mustn't have flattened we mustn't have flattened you mustn't have flattened they mustn't have flattened	I mustn't have been flattening you mustn't have been flattening he mustn't have been flattening we mustn't have been flattening you mustn't have been flattening they mustn't have been flattening

Interrogative form

Simple form	V-ing form
must I flatten? must you flatten? must he flatten? must we flatten? must you flatten? must they flatten?	must I be flattening? must you be flattening? must he be flattening? must we be flattening? must you be flattening? must they be flattening?
Perfect	V-ing perfect
must I have flattened? must you have flattened? must he have flattened? must we have flattened? must you have flattened? must they have flattened?	must I have been flattening? must you have been flattening? must he have been flattening? must we have been flattening? must you have been flattening? must they have been flattening?

Interro-negative form

Simple form	V-ing form
mustn't I flatten? mustn't you flatten? mustn't he flatten? mustn't we flatten? mustn't you flatten? mustn't they flatten?	mustn't I be flattening? mustn't you be flattening? mustn't he be flattening? mustn't we be flattening? mustn't you be flattening? mustn't they be flattening?
Perfect	V-ing perfect
mustn't I have flattened? mustn't you have flattened? mustn't he have flattened? mustn't we have flattened? mustn't you have flattened? mustn't they have flattened?	mustn't I have been flattening? mustn't you have been flattening? mustn't he have been flattening? mustn't we have been flattening? mustn't you have been flattening? mustn't they have been flattening?