  A practical method is developed to deal with the second quantization of the
many-body system containing the composite particles. In our treatment, the
modes associated with composite particles are regarded approximately as
independent ones compared with those of unbound particles. The field operators
of the composite particles thus arise naturally in the second quantization
Hamiltonian. To be emphasized, the second quantization Hamiltonian has the
regular structures which correspond clearly to different physical processes.
