  Considering the quintom model with arbitrary potential, it is shown that
there always exists a solution which evolves from w > -1 region to w < -1
region. The problem is restricted to the slowly varying potentials, i.e. the
slow-roll approximation. It is seen that the rate of this phase transition only
depends on the energy density of matter at transition time, which itself is
equal to the kinetic part of quintom energy density at that time. The
perturbative solutions of the fields are also obtained.
