With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
Since
then
,
electricity
has
been
generated
mostly
from
hydropower
and
nuclear
power
.
Since:O
then:O
,:O
electricity:O
has:O
been:O
generated:O
mostly:O
from:O
hydropower:O
and:O
nuclear:O
power:O
.:O