  The temperatures of the plasma in the supernova remnants (SNRs) are initially
very low just after the shock heating. The electron temperature (kT_{e})
increases quickly by Coulomb interaction, and then the energetic electrons
gradually ionize atoms to increase the ionization temperature (kT_{i}). The
observational fact is that most of the young and middle-to-old aged SNRs have
lower kT_{i} than kT_{e} after the shock heating. The temperature evolution in
the shell-like SNRs has been explained by this ionizing plasma (IP) scenario.
On the other hand, in the last decade, a significant fraction of the mixed
morphology SNRs was found to exhibit a recombining plasma (RP) with higher
kT_{i} than kT_{e}. The origin and the evolution mechanism of the RP SNRs have
been puzzling. To address this puzzle, this paper presents the kT_{e} and
kT_{i} profiles using the observed results by follow-up Suzaku observations,
and then proposes a new scenario for the temperature and morphology evolutions
in the IP and RP SNRs.
