With no explanation, label each line with "location-GPE", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
It
became
the
mainstay
of
American
telephone
service
well
into
the
1950s
,
and
was
followed
by
the
model
500
telephone
starting
in
1950
,
which
became
the
most
extensively
produced
telephone
model
in
the
industry
's
history
.
It:O
became:O
the:O
mainstay:O
of:O
American:location-GPE
telephone:O
service:O
well:O
into:O
the:O
1950s:O
,:O
and:O
was:O
followed:O
by:O
the:O
model:O
500:O
telephone:O
starting:O
in:O
1950:O
,:O
which:O
became:O
the:O
most:O
extensively:O
produced:O
telephone:O
model:O
in:O
the:O
industry:O
's:O
history:O
.:O