With no explanation, label each line with "O", "other-astronomything", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
On
15
April
2015
,
Pluto
was
imaged
showing
a
possible
polar
cap
.
On:O
15:O
April:O
2015:O
,:O
Pluto:other-astronomything
was:O
imaged:O
showing:O
a:O
possible:O
polar:O
cap:O
.:O