  ALMA data toward QSO J1851+0035 ($l$=$33.498^{\circ}$, $b$=$+0.194^{\circ}$)
were used to study absorption lines by Galactic molecular gas. We detected 17
species (CO, $^{13}$CO, C$^{18}$O, HCO$^+$, H$^{13}$CO$^+$, HCO, H$_2$CO,
C$_2$H, $c$-C$_3$H, $c$-C$_3$H$_2$, CN, HCN, HNC, CS, SO, SiO, and C) and set
upper limits to 18 species as reference values for chemical models. About 20
independent velocity components at 4.7-10.9 kpc from the Galactic Center were
identified. Their column density and excitation temperature estimated from the
absorption study, as well as the CO intensity distributions obtained from the
FUGIN survey, indicate that the components with $\tau$ $\lesssim$ 1 correspond
to diffuse clouds or cloud outer edges. Simultaneous multiple-Gaussian fitting
of CO $J$=1-0 and $J$=2-1 absorption lines shows that these are composed of
narrow- and broad-line components. The kinetic temperature empirically expected
from the high HCN/HNC isomer ratio ($\gtrsim$4) reaches $\gtrsim$40 K and the
corresponding thermal width accounts for the line widths of the narrow-line
components. CN-bearing molecules and hydrocarbons have tight and linear
correlations within the groups. The CO/HCO$^+$ abundance ratio showed a
dispersion as large as 3 orders of magnitude with a smaller ratio in a smaller
$N$(HCO$^+$) (or lower $A_{\rm V}$) range. Some of the velocity components are
detected in single-dish CO emission and ALMA HCO$^+$ absorption but without
corresponding ALMA CO absorption. This may be explained by the mixture of
clumpy CO emitters not resolved with the $\sim$1 pc single-dish beam surrounded
by extended components with a very low CO/HCO$^+$ abundance ratio (i.e.,
CO-poor gas).
