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 ":".
This
was
the
first
time
that
a
comet
was
visited
twice
.
This:O
was:O
the:O
first:O
time:O
that:O
a:O
comet:O
was:O
visited:O
twice:O
.:O