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 must not butt you must not butt she must not butt we must not butt you must not butt they must not butt
V-ing form
I must not be butting you must not be butting she must not be butting we must not be butting you must not be butting they must not be butting
Perfect
I must not have butted you must not have butted she must not have butted we must not have butted you must not have butted they must not have butted
V-ing perfect
I must not have been butting you must not have been butting she must not have been butting we must not have been butting you must not have been butting they must not 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
must I not butt? must you not butt? must she not butt? must we not butt? must you not butt? must they not butt?
V-ing form
must I not be butting? must you not be butting? must she not be butting? must we not be butting? must you not be butting? must they not be butting?
Perfect
must I not have butted? must you not have butted? must she not have butted? must we not have butted? must you not have butted? must they not have butted?
V-ing perfect
must I not have been butting? must you not have been butting? must she not have been butting? must we not have been butting? must you not have been butting? must they not have been butting?