1) There is evidence that prehistoric humans used fire ___ 400,000 B. C.
2) In the late 1800’s Ellen Richards, began work in the new field of “sanitary science” which was concerned with waste removal, water purification and ___.
3) ___ red clover, high in protein content, is an extremely important leguminous hay and pasture plant of the eastern United States.
4) The topology of Mars is more ___ than that of any other planet.
5) Ostriches are ___ of living birds, attaining a height from crown to foot of about 2.4 meters and a weight of up to 136 kilograms.
6) The glaciers that reached the Pacific Coast were valley glaciers, and between those tongues of ice ___ that allowed the original forests to survive.
7) ___ orbits the Sun, Uranus rotates on its axis, an imaginary line through its center.
8) ___ duties are placed on commodities according to their value.
9) ___ about individuals who really existed and things that actually happened.
10) ___ matter in one form is transmuted to another form, a phase change is said to have taken place.