Metal -a solid material that is hard, shiny, malleable, fusible, and ductile, with electrical and thermal conductivity.\
nonmetal an element or substance that is not a metal.
We see the so called " near side " of the moon. Because the moon spins in the exact rotational period we see the same side of the moon every time we look at it .
Ventilation is the act of moving/pushing air into and out of the lungs.
Complex organisms need cells that can perform many different functions. they need to be supported on a cellular level. Without specialized cells you they won't be able to perform different functions.