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