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 ":".
Virtual
economies
also
exist
in
life
simulation
games
which
may
have
taken
the
most
radical
steps
toward
linking
a
virtual
economy
with
the
real
world
.
Virtual:O
economies:O
also:O
exist:O
in:O
life:O
simulation:O
games:O
which:O
may:O
have:O
taken:O
the:O
most:O
radical:O
steps:O
toward:O
linking:O
a:O
virtual:O
economy:O
with:O
the:O
real:O
world:O
.:O