  We investigate the orbital histories of Virgo galaxies at various stages of
HI gas stripping. In particular, we compare the location of galaxies with
different HI morphology in phase space. This method is a great tool for tracing
the gas stripping histories of galaxies as they fall into the cluster. Most
galaxies at the early stage of HI stripping are found in the first infall
region of Virgo, while galaxies undergoing active HI stripping mostly appear to
be falling in or moving out near the cluster core for the first time. Galaxies
with severely stripped, yet symmetric, HI disks are found in one of two
locations. Some are deep inside the cluster, but others are found in the
cluster outskirts with low orbital velocities. We suggest that the latter group
of galaxies belong to a "backsplash" population. These present the clearest
candidates for backsplashed galaxies observationally identified to date. We
further investigate the distribution of a large sample of HI-detected galaxies
toward Virgo in phase space, confirming that most galaxies are stripped of
their gas as they settle into the gravitational potential of the cluster. In
addition, we discuss the impact of tidal interactions between galaxies and
group preprocessing on the HI properties of the cluster galaxies, and link the
associated star formation evolution to the stripping sequence of cluster
galaxies.
