  The observed suppression of high-$p_T$ hadron spectra, finite azimuthal
anisotropy, disappearance of jet-like back-to-back correlations, and their
centrality dependence in $Au+Au$ collisions at RHIC are shown to be
quantitatively described by jet quenching within a pQCD parton model. The
difference between $h^{\pm}$ and $\pi^0$ suppression in intermediate $p_T$ is
consistent with the observed $(K+p)/\pi$ enhancement which should disappear at
$p_T>6$ GeV/$c$. The suppression of back-to-back correlations is shown to be
directly related to the medium modification of jet fragmentation functions(FF).
