I must regress you must regress she must regress we must regress you must regress they must regress
V-ing form
I must be regressing you must be regressing she must be regressing we must be regressing you must be regressing they must be regressing
Perfect
I must have regressed you must have regressed she must have regressed we must have regressed you must have regressed they must have regressed
V-ing perfect
I must have been regressing you must have been regressing she must have been regressing we must have been regressing you must have been regressing they must have been regressing
Negation
Simple form
I must not regress you must not regress she must not regress we must not regress you must not regress they must not regress
V-ing form
I must not be regressing you must not be regressing she must not be regressing we must not be regressing you must not be regressing they must not be regressing
Perfect
I must not have regressed you must not have regressed she must not have regressed we must not have regressed you must not have regressed they must not have regressed
V-ing perfect
I must not have been regressing you must not have been regressing she must not have been regressing we must not have been regressing you must not have been regressing they must not have been regressing
Interrogative form
Simple form
must I regress? must you regress? must she regress? must we regress? must you regress? must they regress?
V-ing form
must I be regressing? must you be regressing? must she be regressing? must we be regressing? must you be regressing? must they be regressing?
Perfect
must I have regressed? must you have regressed? must she have regressed? must we have regressed? must you have regressed? must they have regressed?
V-ing perfect
must I have been regressing? must you have been regressing? must she have been regressing? must we have been regressing? must you have been regressing? must they have been regressing?
Interro-negative form
Simple form
must I not regress? must you not regress? must she not regress? must we not regress? must you not regress? must they not regress?
V-ing form
must I not be regressing? must you not be regressing? must she not be regressing? must we not be regressing? must you not be regressing? must they not be regressing?
Perfect
must I not have regressed? must you not have regressed? must she not have regressed? must we not have regressed? must you not have regressed? must they not have regressed?
V-ing perfect
must I not have been regressing? must you not have been regressing? must she not have been regressing? must we not have been regressing? must you not have been regressing? must they not have been regressing?