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