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