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