The movement of a characteristic from one place to another over a period of time
a countermigration stream
b migration stream
c diffusion

Why do we always see the same side of the moon? 1. the moon rotates at the same speed as the earth rotates. 2. the moon revolves around the earth at the same rate the earth rotates on its axis. 3. the moon rotates on its axis at about the same speed as it revolves around the earth.