Unlike aircraft however, flying animals must be very light to achieve flight, the largest living flying animals being birds of around 20 kilograms.
(the largest living flying animals; being; birds of around 20 kilograms) (flying animals; must be; very light to achieve flight) (flying animals; to achieve; flight)
the largest living flying animals flying animals flying animals
being must be to achieve
birds of around 20 kilograms
very light to achieve flight
flight