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