  The Kerr-Newman metric is used to discuss the averagely measured speed of
light along the radial direction at the black hole from a weak-gravitation
reference frame such as an observer on Earth. The velocity equation of light at
the black hole is represented in the spherical coordinate (r, thita, phi) and
the main parameters are the Schwarzschild radius RS, the rotation term a, and
the charged term RQ. From the calculations, the averagely radial speed of light
from r=Rs to r= (alpha)Rs with alpha>1 is possibly exceeding the speed of light
c in free space by an observer in a reference frame far away from the black
hole like on Earth. The result extends to the large r region when the rotation
of the black hole is very high or the charge is large enough. This averagely
radial speed finally goes to c in a large distance away from the black hole. We
also propose a new explanation based on our results that the observation of the
faster-than-light particle is due to the light bending near the black hole or
supermassive star with very strong gravity. Finally, we also give explanation
that the propagation speed of gravity shall not be faster than the
corresponding speed of light.
