one-to-one correspondence with the training goals, that is to
say, the means to realize those goals are diverse, which remains
the same even in restraint of such external conditions as
teaching hours and school characteristics, etc. This problem
can, in mathematics, boil down to the problem of optimization.
Nevertheless, we can not work out the optimal solution because
of the complexity and time-variance of the problem but can
make some optimization to seek a satisfying answer