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Persons in specified occupations and businesses have a 1_______ or permit. Physicians, teachers, lawyers, plumbers, electricians, pharmacists, real estate brokers, insurance agents, and building contractors are among such persons. Licensing 2_______ attempt to prevent incompetent and dishonest persons from harming the public. In any event, no 3_______ made by or with а person who 4_______ the required competency license may be enforced by the unlicensed person.