What term refers to a hydroelectric power structure that uses two reservoirs?

1) what three conditions must be present for minerals to form through natural processes? 2) why are minerals considered inorganic substances? 3) how do oxides differ from other minerals that contain oxygen atoms? 4) how is a sulfide different from a sulfate? what makes native elements unique?

Can someone i have no idea of how to do this.

Guard cells control which event? the growth of plants capture of solar energy gas exchange in leaves water absorption in roots