English verb conjugation
MUST RUFF

Regular verb: ruff - ruffed - ruffed

Affirmation

Simple form	V-ing form
I must ruff you must ruff he must ruff we must ruff you must ruff they must ruff	I must be ruffing you must be ruffing he must be ruffing we must be ruffing you must be ruffing they must be ruffing
Perfect	V-ing perfect
I must have ruffed you must have ruffed he must have ruffed we must have ruffed you must have ruffed they must have ruffed	I must have been ruffing you must have been ruffing he must have been ruffing we must have been ruffing you must have been ruffing they must have been ruffing

Negation

Simple form	V-ing form
I mustn't ruff you mustn't ruff he mustn't ruff we mustn't ruff you mustn't ruff they mustn't ruff	I mustn't be ruffing you mustn't be ruffing he mustn't be ruffing we mustn't be ruffing you mustn't be ruffing they mustn't be ruffing
Perfect	V-ing perfect
I mustn't have ruffed you mustn't have ruffed he mustn't have ruffed we mustn't have ruffed you mustn't have ruffed they mustn't have ruffed	I mustn't have been ruffing you mustn't have been ruffing he mustn't have been ruffing we mustn't have been ruffing you mustn't have been ruffing they mustn't have been ruffing

Interrogative form

Simple form	V-ing form
must I ruff? must you ruff? must he ruff? must we ruff? must you ruff? must they ruff?	must I be ruffing? must you be ruffing? must he be ruffing? must we be ruffing? must you be ruffing? must they be ruffing?
Perfect	V-ing perfect
must I have ruffed? must you have ruffed? must he have ruffed? must we have ruffed? must you have ruffed? must they have ruffed?	must I have been ruffing? must you have been ruffing? must he have been ruffing? must we have been ruffing? must you have been ruffing? must they have been ruffing?

Interro-negative form

Simple form	V-ing form
mustn't I ruff? mustn't you ruff? mustn't he ruff? mustn't we ruff? mustn't you ruff? mustn't they ruff?	mustn't I be ruffing? mustn't you be ruffing? mustn't he be ruffing? mustn't we be ruffing? mustn't you be ruffing? mustn't they be ruffing?
Perfect	V-ing perfect
mustn't I have ruffed? mustn't you have ruffed? mustn't he have ruffed? mustn't we have ruffed? mustn't you have ruffed? mustn't they have ruffed?	mustn't I have been ruffing? mustn't you have been ruffing? mustn't he have been ruffing? mustn't we have been ruffing? mustn't you have been ruffing? mustn't they have been ruffing?