  Using the PQCD method we calculate the W-exchange and the W-annihilation
processes of B mesons, which in general involve a charm quark or anti-quark in
the final state. The nonvanishing amplitudes of these processes are found to be
suppressed by a factor of $m_c/m_b$ compared to the tree or the time-like
penguin processes, but some of them are within the reach of observation at the
future B-factories, and $\bar B_d^0 \to D^+_s K^-$ whose branching ratio is
found to be $6.6 \times 10^{-6}$ can be found even before the B-factory era.
Comparisons with the results based on the BSW model are also given.
