Answer to Question 1
For the past 40 years, the percentage of America's steel produced in vertically integrated firms like U.S. Steel has declined. This is because mini mills have replaced large blast furnaces. Unlike blast furnaces, electric furnaces can be turned on and off almost at will. They often operate late at night when electricity rates are very low, because utilities cannot turn their generators off and restart them in time to meet the next day's load. It is more efficient for a mini-mill to use the market than to integrate upstream.
Answer to Question 2
D
Extinct North American Megafauna
A biological profile from the bony remains of an individual may be preferable to a DNA profile for a
This portrait of Thomas Jefferson is considered an accurate likeness, painted when he was thirty-sev
In American Progress (1872), John Gast depicts a feminized (and eroticized) America moving westward,
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North American temperate deciduous forest. Forest soil profile at right.