  We study three-body nonleptonic decays $B\to VVP$ by introducing two-meson
distribution amplitudes for the vector-pseudoscalar pair, such that the
analysis is simplified into the one for two-body decays. The twist-2 and
twist-3 $\phi K$ two-meson distribution amplitudes, associated with
longitudinally and transversely polarized $\phi$ mesons, are constrained by the
experimental data of the $\tau\to\phi K\nu$ and $B\to\phi K\gamma$ branching
ratios. We then predict the $B\to\phi K\gamma$ and $B\to\phi\phi K$ decay
spectra in the $\phi K$ invariant mass. Since the resonant contribution in the
$\phi K$ channel is negligible, the above decay spectra provide a clean test
for the application of two-meson distribution amplitudes to three-body $B$
meson decays.
