With no explanation, label each line with "O", "other-chemicalthing", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
Dimethylamphetamine
has
occasionally
been
found
in
illicit
methamphetamine
laboratories
,
but
is
usually
an
impurity
rather
than
the
desired
product
.
Dimethylamphetamine:other-chemicalthing
has:O
occasionally:O
been:O
found:O
in:O
illicit:O
methamphetamine:O
laboratories:O
,:O
but:O
is:O
usually:O
an:O
impurity:O
rather:O
than:O
the:O
desired:O
product:O
.:O