With no explanation, label each line with "product-airplane", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
LERX
were
first
used
on
the
Northrop
F-5
``
Freedom
fighter
''
which
flew
in
1959
,
and
have
since
become
commonplace
on
many
combat
aircraft
.
LERX:O
were:O
first:O
used:O
on:O
the:O
Northrop:product-airplane
F-5:product-airplane
``:product-airplane
Freedom:product-airplane
fighter:product-airplane
'':product-airplane
which:O
flew:O
in:O
1959:O
,:O
and:O
have:O
since:O
become:O
commonplace:O
on:O
many:O
combat:O
aircraft:O
.:O