<span>Crust, mantle and core (core has 2 layers) </span>
All elements are made of "atoms", and an atom is made up from 3 basic particles: Electrons are particles with a negative charge :)
In terms of function, bird wings are used to flap transversely, whereas butterfly wings are used to flap laterally. In terms of structure, bird wings are filled with hollow bones for easier flight, whereas butterfly wings are structured by scales and tiny hairs.
Answer:
movement to and fro or around something, especially that of fluid in a closed system.
