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 ":".
This
layer
protects
the
metal
from
further
oxidation
.
This:O
layer:O
protects:O
the:O
metal:O
from:O
further:O
oxidation:O
.:O