With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
Over
the
years
,
our
areas
of
ignorance
have
progressively
narrowed
.
Over:O
the:O
years:O
,:O
our:O
areas:O
of:O
ignorance:O
have:O
progressively:O
narrowed:O
.:O