With no explanation, label each line with "O", "event-election", "person-politician", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
On
August
23
,
2008
,
the
Obama
campaign
announced
that
Biden
would
become
Barack
Obama
's
running
mate
.
On:O
August:O
23:O
,:O
2008:O
,:O
the:O
Obama:event-election
campaign:event-election
announced:O
that:O
Biden:person-politician
would:O
become:O
Barack:person-politician
Obama:person-politician
's:O
running:O
mate:O
.:O