  We present results obtained towards the HII regions N159, N166, and N132 from
the emission of several molecular lines in the 345 GHz window. Using ASTE we
mapped a 2.4' $\times$ 2.4' region towards the molecular cloud N159-W in the
$^{13}$CO J=3-2 line and observed several molecular lines at an IR peak very
close to a massive young stellar object. $^{12}$CO and $^{13}$CO J=3-2 were
observed towards two positions in N166 and one position in N132. The $^{13}$CO
J=3-2 map of the N159-W cloud shows that the molecular peak is shifted
southwest compared to the peak of the IR emission. Towards the IR peak we
detected emission from HCN, HNC, HCO$^{+}$, C$_{2}$H J=4-3, CS J=7-6, and
tentatively C$^{18}$O J=3-2. This is the first reported detection of these
molecular lines in N159-W. The analysis of the C$_{2}$H line yields more
evidence supporting that the chemistry involving this molecular species in
compact and/or UCHII regions in the LMC should be similar to that in Galactic
ones. A non-LTE study of the CO emission suggests the presence of both cool and
warm gas in the analysed region. The same analysis for the CS, HCO$^{+}$, HCN,
and HNC shows that it is very likely that their emissions arise mainly from
warm gas with a density between $5 \times 10^5$ to some $10^6$ cm$^{-3}$. The
obtained HCN/HNC abundance ratio greater than 1 is compatible with warm gas and
with an star-forming scenario. From the analysis of the molecular lines
observed towards N132 and N166 we propose that both regions should have similar
physical conditions, with densities of about 10$^3$ cm$^{-3}$.
