  Based on a generalized Yang-Mills framework, gravitational and strong
interactions can be unified in analogy with the unification in the electroweak
theory. By gauging $T(4) \times [SU(3)]_{color} $ in flat space-time, we have a
unified model of chromo-gravity with a new tensor gauge field, which couples
universally to all gluons, quarks and anti-quarks. The space-time translational
gauge symmetry assures that all wave equations of quarks and gluons reduce to a
Hamilton-Jacobi equation with the same `effective Riemann metric tensors' in
the geometric-optics (or classical) limit. The emergence of effective metric
tensors in the classical limit is essential for the unified model to agree with
experiments. The unified model suggests that all gravitational, strong and
electroweak interactions appear to be dictated by gauge symmetries in the
generalized Yang-Mills framework.
