With no explanation, label each line with "O", "other-chemicalthing", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
The
main
use
of
TOPO
is
in
solvent
extraction
of
metals
,
especially
uranium
.
The:O
main:O
use:O
of:O
TOPO:other-chemicalthing
is:O
in:O
solvent:O
extraction:O
of:O
metals:O
,:O
especially:O
uranium:O
.:O