  Nuclear Fermi momentum is a basic property of a nucleus where many nucleons
dwell. However, in experiments only the nuclear Fermi momenta of just a few
nuclei are measured using quasielastic electron scattering on the nuclear
targets so far. Particularly, we still do not know experimentally the Fermi
momentum of the lightest nucleon composite -- the deuteron. In this paper, we
apply both gaussian distribution and Cauchy distribution to describe the
quasielastic peak in the cross section of electron-nucleus scattering. The dip
of the cross-section ratio at about $x_{\rm B}=1$ is explained with the nuclear
Fermi momentum. By performing the least-square fits to the published CLAS data
in the narrow kinematic region of quasielastic scattering, we obtain the
nuclear Fermi momenta of $^{2}$H, $^{27}$Al and $^{56}$Fe, which are $116\pm 7$
MeV/c, $232\pm 27$ MeV/c, and $244\pm 28$ MeV/c respectively. The extracted
nuclear Fermi momenta are compared to the simple calculations based on Fermi
gas model, and the consistencies are found.
