I must regain you must regain he must regain we must regain you must regain they must regain
V-ing form
I must be regaining you must be regaining he must be regaining we must be regaining you must be regaining they must be regaining
Perfect
I must have regained you must have regained he must have regained we must have regained you must have regained they must have regained
V-ing perfect
I must have been regaining you must have been regaining he must have been regaining we must have been regaining you must have been regaining they must have been regaining
Negation
Simple form
I must not regain you must not regain he must not regain we must not regain you must not regain they must not regain
V-ing form
I must not be regaining you must not be regaining he must not be regaining we must not be regaining you must not be regaining they must not be regaining
Perfect
I must not have regained you must not have regained he must not have regained we must not have regained you must not have regained they must not have regained
V-ing perfect
I must not have been regaining you must not have been regaining he must not have been regaining we must not have been regaining you must not have been regaining they must not have been regaining
Interrogative form
Simple form
must I regain? must you regain? must he regain? must we regain? must you regain? must they regain?
V-ing form
must I be regaining? must you be regaining? must he be regaining? must we be regaining? must you be regaining? must they be regaining?
Perfect
must I have regained? must you have regained? must he have regained? must we have regained? must you have regained? must they have regained?
V-ing perfect
must I have been regaining? must you have been regaining? must he have been regaining? must we have been regaining? must you have been regaining? must they have been regaining?
Interro-negative form
Simple form
must I not regain? must you not regain? must he not regain? must we not regain? must you not regain? must they not regain?
V-ing form
must I not be regaining? must you not be regaining? must he not be regaining? must we not be regaining? must you not be regaining? must they not be regaining?
Perfect
must I not have regained? must you not have regained? must he not have regained? must we not have regained? must you not have regained? must they not have regained?
V-ing perfect
must I not have been regaining? must you not have been regaining? must he not have been regaining? must we not have been regaining? must you not have been regaining? must they not have been regaining?