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 must not ruff you must not ruff he must not ruff we must not ruff you must not ruff they must not ruff	I must not be ruffing you must not be ruffing he must not be ruffing we must not be ruffing you must not be ruffing they must not be ruffing
Perfect	V-ing perfect
I must not have ruffed you must not have ruffed he must not have ruffed we must not have ruffed you must not have ruffed they must not have ruffed	I must not have been ruffing you must not have been ruffing he must not have been ruffing we must not have been ruffing you must not have been ruffing they must not 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
must I not ruff? must you not ruff? must he not ruff? must we not ruff? must you not ruff? must they not ruff?	must I not be ruffing? must you not be ruffing? must he not be ruffing? must we not be ruffing? must you not be ruffing? must they not be ruffing?
Perfect	V-ing perfect
must I not have ruffed? must you not have ruffed? must he not have ruffed? must we not have ruffed? must you not have ruffed? must they not have ruffed?	must I not have been ruffing? must you not have been ruffing? must he not have been ruffing? must we not have been ruffing? must you not have been ruffing? must they not have been ruffing?