  We examine the NMR experimental data for the normal state of
YBa$_2$Cu$_3$O$_{7-\delta}$ within the Fermi-liquid approach. We show that the
observed temperature dependence of the Knight shift and $^{17}$O ($^{89}$Y)
relaxation rate in ``underdoped'' ( $T_c=60\,$K ) compound can be interpreted
as resulting from a peak in the density of states near the Fermi level. The
possible origin of such peak is the quasi-one-dimensional van Hove singularity
in the fermionic spectrum, conjectured by Abrikosov, Gofron and Campuzano. The
proposed spectrum allows us to account for the qualitatively different NMR data
for ``underdoped'' and ``overdoped''( $T_c=90\,$K ) compounds by varying the
value of chemical potential only.
