With no explanation, label each line with "O", "other-chemicalthing", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
Alkenes
can
be
prepared
indirectly
from
alkyl
amines
.
Alkenes:other-chemicalthing
can:O
be:O
prepared:O
indirectly:O
from:O
alkyl:O
amines:O
.:O