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 ":".
Today
downtown
Toronto
contains
dozens
of
notable
skyscrapers
.
Today:O
downtown:O
Toronto:location-GPE
contains:O
dozens:O
of:O
notable:O
skyscrapers:O
.:O