  We consider inhomogeneous Bernoulli measures of the form $\prod_{x\in\Lambda}
p_x$ where $p_x$ are prescribed and uniformly bounded above and below away from
0 and 1. A comparison inequality is proved between the Kawasaki and
Bernoulli-Laplace Dirichlet forms. Together with a recent result of Caputo on
the gap of the Bernoulli-Laplace model, this proves a spectral gap of the
correct order L^{-2} on cubes of side length L for the Kawasaki dynamics. The
two block estimate of hydrodynamic limits is also obtained.
