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 ":".
Heavier
railway
equipment
was
built
and
ordered
to
keep
up
with
the
increased
tonnage
,
and
with
the
heavier
trains
came
heavier
bridges
.
Heavier:O
railway:O
equipment:O
was:O
built:O
and:O
ordered:O
to:O
keep:O
up:O
with:O
the:O
increased:O
tonnage:O
,:O
and:O
with:O
the:O
heavier:O
trains:O
came:O
heavier:O
bridges:O
.:O