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 ":".
Alpha-naphthol
acts
as
a
color
enhancer
,
but
the
color
change
to
red
can
occur
without
it
.
Alpha-naphthol:other-chemicalthing
acts:O
as:O
a:O
color:O
enhancer:O
,:O
but:O
the:O
color:O
change:O
to:O
red:O
can:O
occur:O
without:O
it:O
.:O