IN: Which person is he?
Jack the ripper killed John, but he was not caught yet.
OUT: Jack

IN: Which person is they?
Medics have a tough job of trying to heal the wounded since they normally have to fix them in hostile environments.
OUT: Medics

IN: Which person is he?
Michael asked Jacob to dance because he was lonely.
OUT: Jacob

IN: Which person is he?
Neil Patrick Harris is a better singer than Dave Chappelle,since he does not have time to become a good singer due to his comedy career.
OUT:
Dave Chappelle