I must flat you must flat he must flat we must flat you must flat they must flat
V-ing form
I must be flating you must be flating he must be flating we must be flating you must be flating they must be flating
Perfect
I must have flated you must have flated he must have flated we must have flated you must have flated they must have flated
V-ing perfect
I must have been flating you must have been flating he must have been flating we must have been flating you must have been flating they must have been flating
Negation
Simple form
I mustn't flat you mustn't flat he mustn't flat we mustn't flat you mustn't flat they mustn't flat
V-ing form
I mustn't be flating you mustn't be flating he mustn't be flating we mustn't be flating you mustn't be flating they mustn't be flating
Perfect
I mustn't have flated you mustn't have flated he mustn't have flated we mustn't have flated you mustn't have flated they mustn't have flated
V-ing perfect
I mustn't have been flating you mustn't have been flating he mustn't have been flating we mustn't have been flating you mustn't have been flating they mustn't have been flating
Interrogative form
Simple form
must I flat? must you flat? must he flat? must we flat? must you flat? must they flat?
V-ing form
must I be flating? must you be flating? must he be flating? must we be flating? must you be flating? must they be flating?
Perfect
must I have flated? must you have flated? must he have flated? must we have flated? must you have flated? must they have flated?
V-ing perfect
must I have been flating? must you have been flating? must he have been flating? must we have been flating? must you have been flating? must they have been flating?
Interro-negative form
Simple form
mustn't I flat? mustn't you flat? mustn't he flat? mustn't we flat? mustn't you flat? mustn't they flat?
V-ing form
mustn't I be flating? mustn't you be flating? mustn't he be flating? mustn't we be flating? mustn't you be flating? mustn't they be flating?
Perfect
mustn't I have flated? mustn't you have flated? mustn't he have flated? mustn't we have flated? mustn't you have flated? mustn't they have flated?
V-ing perfect
mustn't I have been flating? mustn't you have been flating? mustn't he have been flating? mustn't we have been flating? mustn't you have been flating? mustn't they have been flating?