English verb conjugation
MUST PUFF

Regular verb: puff - puffed - puffed

Affirmation

Simple form	V-ing form
I must puff you must puff she must puff we must puff you must puff they must puff	I must be puffing you must be puffing she 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 she 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 she 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 she 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 she 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 she 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 she 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 she puff? must we puff? must you puff? must they puff?	must I be puffing? must you be puffing? must she 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 she 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 she 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 she 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 she 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 she 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 she have been puffing? mustn't we have been puffing? mustn't you have been puffing? mustn't they have been puffing?