I must stem you must stem she must stem we must stem you must stem they must stem
V-ing form
I must be stemming you must be stemming she must be stemming we must be stemming you must be stemming they must be stemming
Perfect
I must have stemmed you must have stemmed she must have stemmed we must have stemmed you must have stemmed they must have stemmed
V-ing perfect
I must have been stemming you must have been stemming she must have been stemming we must have been stemming you must have been stemming they must have been stemming
Negation
Simple form
I mustn't stem you mustn't stem she mustn't stem we mustn't stem you mustn't stem they mustn't stem
V-ing form
I mustn't be stemming you mustn't be stemming she mustn't be stemming we mustn't be stemming you mustn't be stemming they mustn't be stemming
Perfect
I mustn't have stemmed you mustn't have stemmed she mustn't have stemmed we mustn't have stemmed you mustn't have stemmed they mustn't have stemmed
V-ing perfect
I mustn't have been stemming you mustn't have been stemming she mustn't have been stemming we mustn't have been stemming you mustn't have been stemming they mustn't have been stemming
Interrogative form
Simple form
must I stem? must you stem? must she stem? must we stem? must you stem? must they stem?
V-ing form
must I be stemming? must you be stemming? must she be stemming? must we be stemming? must you be stemming? must they be stemming?
Perfect
must I have stemmed? must you have stemmed? must she have stemmed? must we have stemmed? must you have stemmed? must they have stemmed?
V-ing perfect
must I have been stemming? must you have been stemming? must she have been stemming? must we have been stemming? must you have been stemming? must they have been stemming?
Interro-negative form
Simple form
mustn't I stem? mustn't you stem? mustn't she stem? mustn't we stem? mustn't you stem? mustn't they stem?
V-ing form
mustn't I be stemming? mustn't you be stemming? mustn't she be stemming? mustn't we be stemming? mustn't you be stemming? mustn't they be stemming?
Perfect
mustn't I have stemmed? mustn't you have stemmed? mustn't she have stemmed? mustn't we have stemmed? mustn't you have stemmed? mustn't they have stemmed?
V-ing perfect
mustn't I have been stemming? mustn't you have been stemming? mustn't she have been stemming? mustn't we have been stemming? mustn't you have been stemming? mustn't they have been stemming?