I must grunt you must grunt she must grunt we must grunt you must grunt they must grunt
V-ing form
I must be grunting you must be grunting she must be grunting we must be grunting you must be grunting they must be grunting
Perfect
I must have grunted you must have grunted she must have grunted we must have grunted you must have grunted they must have grunted
V-ing perfect
I must have been grunting you must have been grunting she must have been grunting we must have been grunting you must have been grunting they must have been grunting
Negation
Simple form
I must not grunt you must not grunt she must not grunt we must not grunt you must not grunt they must not grunt
V-ing form
I must not be grunting you must not be grunting she must not be grunting we must not be grunting you must not be grunting they must not be grunting
Perfect
I must not have grunted you must not have grunted she must not have grunted we must not have grunted you must not have grunted they must not have grunted
V-ing perfect
I must not have been grunting you must not have been grunting she must not have been grunting we must not have been grunting you must not have been grunting they must not have been grunting
Interrogative form
Simple form
must I grunt? must you grunt? must she grunt? must we grunt? must you grunt? must they grunt?
V-ing form
must I be grunting? must you be grunting? must she be grunting? must we be grunting? must you be grunting? must they be grunting?
Perfect
must I have grunted? must you have grunted? must she have grunted? must we have grunted? must you have grunted? must they have grunted?
V-ing perfect
must I have been grunting? must you have been grunting? must she have been grunting? must we have been grunting? must you have been grunting? must they have been grunting?
Interro-negative form
Simple form
must I not grunt? must you not grunt? must she not grunt? must we not grunt? must you not grunt? must they not grunt?
V-ing form
must I not be grunting? must you not be grunting? must she not be grunting? must we not be grunting? must you not be grunting? must they not be grunting?
Perfect
must I not have grunted? must you not have grunted? must she not have grunted? must we not have grunted? must you not have grunted? must they not have grunted?
V-ing perfect
must I not have been grunting? must you not have been grunting? must she not have been grunting? must we not have been grunting? must you not have been grunting? must they not have been grunting?