  We look at two methods to determine the weak phases $\phi_2$ and $\phi_3$
from $B \to \pi\pi$ and $K\pi$ decays within the perturbative QCD approach. We
obtain quite interesting bounds on $\phi_2$ and $\phi_3$ from recent
experimental measurements in asymmetric B-factory: $55^o \leq \phi_2 \leq
100^o$ and $51^o \leq \phi_3 \leq 129^o$. Specially we predict the possibility
of large direct CP violation effect in $B^0 \to \pi^{+}\pi^{-}$ decay with
$A_{cp}^{dir}(B\to \pi^{+} \pi^{-})=(23\pm7)$ %.
