  Transit spectroscopy is the most frequently used technique to reveal the
atmospheric properties of exoplanets, while that at high resolution has the
advantage to resolve the small Doppler shift of spectral lines, and the trace
signal of the exoplanet atmosphere can be separately extracted. We obtain the
transmission spectra of the extrasolar planet WASP-85Ab, a hot Jupiter in a
2.655-day orbit around a G5, V=11.2 mag host star, observed by high-resolution
spectrograph ESPRESSO at the Very Large Telescope array for three transits. We
present an analysis of the Rossiter-McLaughlin effect on WASP-85A, and
determine a spin-orbit angle ${\lambda = -16.155^{\circ}}^{+2.916}_{-2.879}$,
suggesting that the planet is in an almost aligned orbit. Combining the
transmission spectra of three nights, we tentatively detected H$\alpha$ and Ca
II absorption with $\gtrapprox 3\sigma$ via direct visual inspection of the
transmission spectra with the Center-to-Limb variation and the
Rossiter-McLaughlin effects removed, which still remain visible after excluding
the cores of these strong lines with a 0.1 A mask. These spectral signals seems
likely to origin from the planetary atmosphere, but we can not fully exclude
their stellar origins. Via the cross-correlation analysis of a set of atoms and
molecules, Li I is marginally detected at $\sim4\sigma$ level, suggesting that
Li might be present in the atmosphere of WASP-85Ab.
