With no explanation, label each line with "person-athlete", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
Brian
Baker
and
Mackenzie
McDonald
were
the
defending
champions
but
only
McDonald
chose
to
defend
his
title
,
partnering
Miķelis
Lībietis
.
Brian:person-athlete
Baker:person-athlete
and:O
Mackenzie:person-athlete
McDonald:person-athlete
were:O
the:O
defending:O
champions:O
but:O
only:O
McDonald:person-athlete
chose:O
to:O
defend:O
his:O
title:O
,:O
partnering:O
Miķelis:person-athlete
Lībietis:person-athlete
.:O