  This paper gives high-precision theoretical predictions for cross sections of
the process $e^+e^- \to \gamma Z$ for future electron-positron colliders. The
calculations are performed using the SANC system. They include complete
one-loop electroweak radiative corrections, as well as longitudinal
polarization of the initial state. Numerical results are given for the
center-of-mass system energy range $\sqrt{s} = 250 - 1000$ GeV with various
polarization degrees in the $\alpha(0)$ and $G_\mu$ EW schemes. This study is a
contribution to the research program of the CEPC project being under
development in China.
