During the last twenty years, which category of the U.S. population has experienced the largest gains in average income?
a. The lowest-paid 20 percent
b. The middle 20 percent
c. The highest-paid 20 percent
d. All income categories have experienced about the same level of upward social mobility.
Question 2
During the last three decades, the real income of African American families in the United States has ________
a. gone down a lot.
b. kept pace with the gains made by white people.
c. gone up a lot.
d. changed very little.
Animal extinctions and human population growth.
The spotted wobbegong is the largest wobbegong shark, reaching a length of around 3 m
Goliath birdeater (Theraphosa blondi), the largest spider, next to a ruler.
Uranus revolves around the Sun once every 84 Earth years. Its average distance from the Sun is rough
Ngandong calottes from Java are the youngest H. erectus fossils at perhaps 27,000-50,000 years old.
A passenger train crosses Stony Creek Bridge in the Rocky Mountains in 1878. Railroads were importan