With no explanation, label each line with "O", "building-airport", "organization-company", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-hospital" preceded by ":".
This
service
ended
when
Delta
closed
its
hub
operation
at
Dallas/Fort
Worth
International
Airport
(
DFW
)
.
This:O
service:O
ended:O
when:O
Delta:organization-company
closed:O
its:O
hub:O
operation:O
at:O
Dallas/Fort:building-airport
Worth:building-airport
International:building-airport
Airport:building-airport
(:O
DFW:building-airport
):O
.:O