I must sneak you must sneak she must sneak we must sneak you must sneak they must sneak
V-ing form
I must be sneaking you must be sneaking she must be sneaking we must be sneaking you must be sneaking they must be sneaking
Perfect
I must have snuck you must have snuck she 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 she 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 she 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 she 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 she 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 she 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 she sneak? must we sneak? must you sneak? must they sneak?
V-ing form
must I be sneaking? must you be sneaking? must she be sneaking? must we be sneaking? must you be sneaking? must they be sneaking?
Perfect
must I have snuck? must you have snuck? must she 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 she 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 she 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 she 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 she 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 she have been sneaking? mustn't we have been sneaking? mustn't you have been sneaking? mustn't they have been sneaking?