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 ":".
In
the
third
step
,
this
compound
is
oxidized
by
red
lead
to
carbazole
itself
.
In:O
the:O
third:O
step:O
,:O
this:O
compound:O
is:O
oxidized:O
by:O
red:O
lead:O
to:O
carbazole:other-chemicalthing
itself:O
.:O