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 ":".
The
valley
floors
are
covered
with
loose
gravel
,
in
which
ice
wedge
polygonal
patterned
ground
may
be
observed
.
The:O
valley:O
floors:O
are:O
covered:O
with:O
loose:O
gravel:O
,:O
in:O
which:O
ice:O
wedge:O
polygonal:O
patterned:O
ground:O
may:O
be:O
observed:O
.:O