  We employ the multipole expansion within the unified electroweak theory to
develop a complete calculation method of the electron scattering cross section
for light nuclei. The specific calculations for 6,7Li and 7Be nuclei indicate
that the conventional impulse approximation can be applied to the
electron-nucleus scattering only when the incident electron energy does not
exceed twice the nucleon mass. In addition, the quasi-elastic scattering cross
section of 7Li in the excitation from its ground state to the nearest excited
state and that of elastic scattering in the ground state are independently
treated, whereas they have not been separately measured in experiments. The
obtained scattering cross sections corresponding to an appropriate adjustment
of the harmonic oscillator parameter along with the V-A structure interpret
reasonably well the available experimental data at MeV energies and provide
predictive information at GeV energies. This gives new perspectives in studying
the structure of nuclei and the weak interactions via electron or lepton
scattering at high (GeV) energies, considering nuclei rather than quarks.
