  The equation of state for neutron matter is calculated within relativistic
Hartree-Fock approximation. The tensor couplings of vector mesons to baryons
are included, and the change of baryon internal structure in matter is also
considered using the quark-meson coupling model. We obtain the maximum
neutron-star mass of $\sim 2.0 M_\odot$, which is consistent with the recently
observed, precise mass, $1.97\pm0.04 M_{\odot}$. The Fock contribution is very
important and, in particular, the inclusion of tensor coupling is vital to
obtain such large mass. The baryon structure variation in matter also enhances
the mass of a neutron star.
