With no explanation, label each line with "O", "other-astronomything", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
His
research
in
solar
variation
helped
provide
evidence
of
the
greenhouse
effect
on
the
Earth
's
climate
in
the
late
20th
century
.
His:O
research:O
in:O
solar:O
variation:O
helped:O
provide:O
evidence:O
of:O
the:O
greenhouse:O
effect:O
on:O
the:O
Earth:other-astronomything
's:O
climate:O
in:O
the:O
late:O
20th:O
century:O
.:O