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 ":".
Two
other
aircraft
used
over
the
last
two
decades
for
the
same
purpose
raised
controversy
.
Two:O
other:O
aircraft:O
used:O
over:O
the:O
last:O
two:O
decades:O
for:O
the:O
same:O
purpose:O
raised:O
controversy:O
.:O