With no explanation, label each line with "O", "person-artist/author", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
It
is
uncertain
when
Tudur
Aled
started
to
write
poetry
.
It:O
is:O
uncertain:O
when:O
Tudur:person-artist/author
Aled:person-artist/author
started:O
to:O
write:O
poetry:O
.:O