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 ":".
These
units
were
constructed
of
narrow
rolling
stock
.
These:O
units:O
were:O
constructed:O
of:O
narrow:O
rolling:O
stock:O
.:O