Fishes today have complex gill structures to obtain the oxygen they require.
(the oxygen; require; they) (Fishes today; have; complex gill structures) Context(Fishes today have,List([0, 17))):(Fishes today; have complex gill structures to obtain; the oxygen they require)
Fishes today have,List([0, 17))
the oxygen Fishes today Fishes today
require have have complex gill structures to obtain
they
complex gill structures
the oxygen they require