I must snuff you must snuff he must snuff we must snuff you must snuff they must snuff
V-ing form
I must be snuffing you must be snuffing he must be snuffing we must be snuffing you must be snuffing they must be snuffing
Perfect
I must have snuffed you must have snuffed he must have snuffed we must have snuffed you must have snuffed they must have snuffed
V-ing perfect
I must have been snuffing you must have been snuffing he must have been snuffing we must have been snuffing you must have been snuffing they must have been snuffing
Negation
Simple form
I mustn't snuff you mustn't snuff he mustn't snuff we mustn't snuff you mustn't snuff they mustn't snuff
V-ing form
I mustn't be snuffing you mustn't be snuffing he mustn't be snuffing we mustn't be snuffing you mustn't be snuffing they mustn't be snuffing
Perfect
I mustn't have snuffed you mustn't have snuffed he mustn't have snuffed we mustn't have snuffed you mustn't have snuffed they mustn't have snuffed
V-ing perfect
I mustn't have been snuffing you mustn't have been snuffing he mustn't have been snuffing we mustn't have been snuffing you mustn't have been snuffing they mustn't have been snuffing
Interrogative form
Simple form
must I snuff? must you snuff? must he snuff? must we snuff? must you snuff? must they snuff?
V-ing form
must I be snuffing? must you be snuffing? must he be snuffing? must we be snuffing? must you be snuffing? must they be snuffing?
Perfect
must I have snuffed? must you have snuffed? must he have snuffed? must we have snuffed? must you have snuffed? must they have snuffed?
V-ing perfect
must I have been snuffing? must you have been snuffing? must he have been snuffing? must we have been snuffing? must you have been snuffing? must they have been snuffing?
Interro-negative form
Simple form
mustn't I snuff? mustn't you snuff? mustn't he snuff? mustn't we snuff? mustn't you snuff? mustn't they snuff?
V-ing form
mustn't I be snuffing? mustn't you be snuffing? mustn't he be snuffing? mustn't we be snuffing? mustn't you be snuffing? mustn't they be snuffing?
Perfect
mustn't I have snuffed? mustn't you have snuffed? mustn't he have snuffed? mustn't we have snuffed? mustn't you have snuffed? mustn't they have snuffed?
V-ing perfect
mustn't I have been snuffing? mustn't you have been snuffing? mustn't he have been snuffing? mustn't we have been snuffing? mustn't you have been snuffing? mustn't they have been snuffing?