A．After four years of college.
B．After another four years of medical school.
C．After at least one year as interns in a hospital.
D．After their education is complete.

A．The differences in work attitudes of employees in big companies and small companies.
B．The management styles of executives in big companies and small companies.
C．The percentage of employees involved in top management in big companies and small companies.
D．The operation on a first-name basis in big companies and small companies.