English verb conjugation
MUST PUFF

Regular verb: puff - puffed - puffed

Affirmation

Simple form	V-ing form
I must puff you must puff he must puff we must puff you must puff they must puff	I must be puffing you must be puffing he must be puffing we must be puffing you must be puffing they must be puffing
Perfect	V-ing perfect
I must have puffed you must have puffed he must have puffed we must have puffed you must have puffed they must have puffed	I must have been puffing you must have been puffing he must have been puffing we must have been puffing you must have been puffing they must have been puffing

Negation

Simple form	V-ing form
I must not puff you must not puff he must not puff we must not puff you must not puff they must not puff	I must not be puffing you must not be puffing he must not be puffing we must not be puffing you must not be puffing they must not be puffing
Perfect	V-ing perfect
I must not have puffed you must not have puffed he must not have puffed we must not have puffed you must not have puffed they must not have puffed	I must not have been puffing you must not have been puffing he must not have been puffing we must not have been puffing you must not have been puffing they must not have been puffing

Interrogative form

Simple form	V-ing form
must I puff? must you puff? must he puff? must we puff? must you puff? must they puff?	must I be puffing? must you be puffing? must he be puffing? must we be puffing? must you be puffing? must they be puffing?
Perfect	V-ing perfect
must I have puffed? must you have puffed? must he have puffed? must we have puffed? must you have puffed? must they have puffed?	must I have been puffing? must you have been puffing? must he have been puffing? must we have been puffing? must you have been puffing? must they have been puffing?

Interro-negative form

Simple form	V-ing form
must I not puff? must you not puff? must he not puff? must we not puff? must you not puff? must they not puff?	must I not be puffing? must you not be puffing? must he not be puffing? must we not be puffing? must you not be puffing? must they not be puffing?
Perfect	V-ing perfect
must I not have puffed? must you not have puffed? must he not have puffed? must we not have puffed? must you not have puffed? must they not have puffed?	must I not have been puffing? must you not have been puffing? must he not have been puffing? must we not have been puffing? must you not have been puffing? must they not have been puffing?