  The paper is devoted to the problem of finding free generators in the fields
of invariants for actions of unipotent groups on affine varieties. We consider
the case when the unipotent group is the unipotent radical in an arbitrary
parabolic subgroup in the reductive group of classical type GL(n), SL(n), O(n)
or Sp(2n). In the explicit form, we present a system of free generators in the
field of invariants for the action of the unipotent radical on the reductive
group by conjugation.
