With no explanation, label each line with "O", "location-bodiesofwater", "location-other", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
The
Natural
Bridge
is
a
stretch
along
which
the
St.
Marks
River
runs
underground
,
after
dropping
into
a
sinkhole
.
The:O
Natural:location-other
Bridge:location-other
is:O
a:O
stretch:O
along:O
which:O
the:O
St.:location-bodiesofwater
Marks:location-bodiesofwater
River:location-bodiesofwater
runs:O
underground:O
,:O
after:O
dropping:O
into:O
a:O
sinkhole:O
.:O