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 ":".
Construction
of
the
first
experimental
prototype
``
Natter
,
Versuchsmuster
1
``
,
was
completed
on
4
October
1944
.
Construction:O
of:O
the:O
first:O
experimental:O
prototype:O
``:O
Natter:product-airplane
,:product-airplane
Versuchsmuster:product-airplane
1:product-airplane
``:O
,:O
was:O
completed:O
on:O
4:O
October:O
1944:O
.:O