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