  Understanding post-common-envelope evolution is important in the studies of
close-binary systems. The majority of all interacting binaries with a compact
object in their system (e.g. cataclysmic variables, X-ray binaries) are thought
to have passed through a common-envelope (CE) phase. Current models of
interacting binaries all assume, as a starting point, that there is no
significant modification of the secondary star compared with a normal star of
similar spectral type. The extent to which the CE significantly alters the
composition of the secondary star has yet to be determined.
  We are studying the M-type secondary in the pre-CV system EG UMa, in order to
determine its atmospheric parameters by comparison with synthetic spectra
generated using PHOENIX. Absorption lines due to several elements have been
used in investigating the stellar parameters of effective temperature, gravity
and over elemental abundance. In addition, we are searching for anomalies due
to s-process elements (such as Ba, Sr, Rb, Y), which may have been deposited in
the atmosphere during the CE stage, and prove that CE evolution has occurred.
  EG UMa displays strong YO absorption bands, which are normally associated
with giants and S stars. These bands may have been formed as a result of an
Y-abundance enhancement introduced by the CE, which would be consistent with
the observed possible Rb and Sr enrichment.
