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 ":".
The
city
was
also
the
center
of
national
and
international
opium
smuggling
during
the
1920s
.
The:O
city:O
was:O
also:O
the:O
center:O
of:O
national:O
and:O
international:O
opium:O
smuggling:O
during:O
the:O
1920s:O
.:O