  The article deals with observations of star-forming regions S231-S235 in
'quasi-thermal' lines of ammonia (NH$_3$), cyanoacetylene (HC$_3$N) and maser
lines of methanol (CH$_3$OH) and water vapor (H$_2$O). S231-S235 regions is
situated in the giant molecular cloud G174+2.5. We selected all massive
molecular clumps in G174+2.5 using archive CO data. For the each clump we
determined mass, size and CO column density. After that we performed
observations of these clumps. We report about first detections of NH$_3$ and
HC$_3$N lines toward the molecular clumps WB89 673 and WB89 668. This means
that high-density gas is present there. Physical parameters of molecular gas in
the clumps were estimated using the data on ammonia emission. We found that the
gas temperature and the hydrogen number density are in the ranges 16-30 K and
2.8-7.2$\times10^3$ cm$^{-3}$, respectively. The shock-tracing line of CH$_3$OH
molecule at 36.2 GHz is newly detected toward WB89 673.
