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 ":".
This
was
to
minimize
the
danger
of
the
destruction
of
the
historic
city
if
the
Germans
sought
to
defend
it
.
This:O
was:O
to:O
minimize:O
the:O
danger:O
of:O
the:O
destruction:O
of:O
the:O
historic:O
city:O
if:O
the:O
Germans:O
sought:O
to:O
defend:O
it:O
.:O