With no explanation, label each line with "O", "organization-politicalparty", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
In
essence
,
the
tactic
involved
meeting
incoming
Luftwaffe
bombing
raids
in
strength
with
a
wing-shaped
formation
of
three
to
five
squadrons
.
In:O
essence:O
,:O
the:O
tactic:O
involved:O
meeting:O
incoming:O
Luftwaffe:organization-politicalparty
bombing:O
raids:O
in:O
strength:O
with:O
a:O
wing-shaped:O
formation:O
of:O
three:O
to:O
five:O
squadrons:O
.:O