With no explanation, label each line with "O", "event-attack/battle/war/militaryconflict", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
During
World
War
II
,
the
line
was
again
entirely
hauled
by
steam
locomotives
and
the
service
was
reduced
considerably
.
During:O
World:event-attack/battle/war/militaryconflict
War:event-attack/battle/war/militaryconflict
II:event-attack/battle/war/militaryconflict
,:O
the:O
line:O
was:O
again:O
entirely:O
hauled:O
by:O
steam:O
locomotives:O
and:O
the:O
service:O
was:O
reduced:O
considerably:O
.:O