  We show in general that there are 108 structure functions in the
proton-deuteron Drell-Yan processes. However, there exist only 22 finite ones
after integrating the cross section over the virtual-photon transverse momentum
\vec Q_T or after taking the limit Q_T->0. There are 11 new structure functions
in comparison with the ones of the proton-proton reactions, and they are
related to the tensor structure of the deuteron. Parton-model analyses indicate
an important tensor structure function V_T^{UQ_0}, which can be measured by a
quadrupole spin asymmetry. The Drell-Yan process has an advantage over lepton
reactions in finding tensor polarized antiquark distributions. We hope that our
studies will be realized in the next-generation RHIC-Spin project and other
ones.
