The US ranks ___ in the world in the total value of its economic production.
A. first
B. second
C. third
D. fourth
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What is America's most important food crop?
A. corn
B. rice
C. barley
D. oat
Service industries account for about ___ of the US gross domestic product.
A. a third
B. half
C. two thirds
D. three fourths
The westward expansion is a demonstration of American ___.
A. individualism
B. patriotism
C. liberalism
D. expansionism
With the arrival of the 20th century, the US became increasingly urbanized, particulary in the ___ cities.
A. Northeast
B. Northwest
C. Southeast
D. Southwest