  We report progress on nuclear structure functions, especially on their
nuclear modifications and a new tensor structure function for the deuteron. To
understand nuclear structure functions is an important step toward describing
nuclei and QCD matters from low to high densities and from low to high energies
in terms of fundamental quark and gluon degrees of freedom beyond conventional
hadron and nuclear physics. It is also practically important for understanding
new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore,
since systematic errors of current neutrino-oscillation experiments are
dominated by uncertainties of neutrino-nucleus interactions, such studies are
valuable for finding new physics beyond current framework. Next, a new
tensor-polarized structure function $b_1$ is discussed for the deuteron. There
was a measurement by HERMES; however, its data are inconsistent with the
conventional convolution estimate based on the standard deuteron model with
D-state admixture. This fact suggests that a new hadronic phenomenon should
exist in the tensor-polarized deuteron at high energies, and it will be
experimentally investigated at JLab from the end of 2010's.
