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 mustn't puff you mustn't puff he mustn't puff we mustn't puff you mustn't puff they mustn't puff	I mustn't be puffing you mustn't be puffing he mustn't be puffing we mustn't be puffing you mustn't be puffing they mustn't be puffing
Perfect	V-ing perfect
I mustn't have puffed you mustn't have puffed he mustn't have puffed we mustn't have puffed you mustn't have puffed they mustn't have puffed	I mustn't have been puffing you mustn't have been puffing he mustn't have been puffing we mustn't have been puffing you mustn't have been puffing they mustn't 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
mustn't I puff? mustn't you puff? mustn't he puff? mustn't we puff? mustn't you puff? mustn't they puff?	mustn't I be puffing? mustn't you be puffing? mustn't he be puffing? mustn't we be puffing? mustn't you be puffing? mustn't they be puffing?
Perfect	V-ing perfect
mustn't I have puffed? mustn't you have puffed? mustn't he have puffed? mustn't we have puffed? mustn't you have puffed? mustn't they have puffed?	mustn't I have been puffing? mustn't you have been puffing? mustn't he have been puffing? mustn't we have been puffing? mustn't you have been puffing? mustn't they have been puffing?