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A．Because these countries need trained personnel to develop their countries.
B．Because the developed countries need more qualified professionals.
C．Because these students can stay on in the developed countries after the training.
D．Because these countries want to establish friendly relationship with the developed countries.

A．Developed countries will employ more qualified professionals from the countries of the South.
B．If no effective methods are adopted by the countries of the South, brain drain will not stop.
C．The educational systems in the developed countries are not very efficient.
D．It is of no use that the developing countries encourage their trained professionals to return.

A．To increase the payment to qualified professionals.
B．To provide good working conditions.
C．To adopt flexible administrative procedures.
D．To confine qualified professionals by using institutional restrictions.