I must stir you must stir she must stir we must stir you must stir they must stir
V-ing form
I must be stirring you must be stirring she must be stirring we must be stirring you must be stirring they must be stirring
Perfect
I must have stirred you must have stirred she 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 she 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 she 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 she 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 she 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 she 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 she stir? must we stir? must you stir? must they stir?
V-ing form
must I be stirring? must you be stirring? must she be stirring? must we be stirring? must you be stirring? must they be stirring?
Perfect
must I have stirred? must you have stirred? must she 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 she 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 she 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 she 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 she 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 she have been stirring? mustn't we have been stirring? mustn't you have been stirring? mustn't they have been stirring?