Hot at the equator causes the air to expand, rise and flow toward the poles.

As many as 50 percent of the income from motion pictures produced in the United States comes from marketing the films abroad.

Financier Andrew Mellon donated most of his magnificent art collection to the National Gallery of Art, where it is now locating.

The manufacture of automobile was extremely expensive until assembly-line techniques made them cheaper to produce

Fossils in 500-millions-year-old rocks demonstrate that life forms in the Cambrian period were mostly marine animals capable of secreting calcium to form shells.

Rainbows in the shape of complete circils are sometimes seen from airplanes because they are not cutting off by the horizon.

Soil temperatures in Death Valley, California, near the Nevada border, have been known to reach 90 of degrees Celsius.

Mary Cassatt's paintings of mothers and children are known for its fine linear rhythm, simple modelings, and harmonies of clear color.

Margaret Brent, because of her skill in managing estates, became ................. largest landholders in colonial Maryland.

Ripe fruit is often stored in a place who contains much carbon dioxide so that the fruit will not decau too rapidly.