  The remarkable observations in the pion induced and charge exchange reactions
on a nucleus are the significant shift and broadening of the $\Delta
(1232)$-peak relative to free pion nucleon scattering. For the forward going
massless leptons, the weak process $(\nu_l,l)$ on a nucleon, according to
Adler's partially conserved axial current theorem, is connected to the pion
nucleon scattering. This mechanism is also applicable to the nucleus.
Therefore, the modification of the $\Delta$-peak in a nucleus can be seen in
the $(\nu_l,l)$ reaction since it is connected to the pion nucleus scattering.
To investigate this issue quantitatively, the double differential cross
sections of the forward going ejectile $l$ energy distribution in the
$(\nu_l,l)$ reaction are calculated in the $\Delta$-excitation region for both
proton and nucleus. The measured pion nucleon and pion nucleus scattering cross
sections in the quoted energy region are used in these reactions as input.
Since the $(\nu_l,l)$ reaction is connected to the pion induced scattering, the
features of the previous reaction is shown analogous to those of the later.
