单项选择题

The figure at the right consists of four semicircles in a large semicircle. If the small semicircles have radii of 1, 2, 3, and 4, what is the perimeter of the shaded region

(A) 10π
(B) 20π
(C)40π
(D)60π
(E) 100π
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单项选择题
In 1988 there were 40,000,000 public school students in the United States, of whom 22% lived in the West. Approximately, how many public school students are projected to be living in the West in 2008
A．9,000,000
B．12,000,000
C．15,000,000
D．24,000,000
E． 66,000,000
单项选择题
A
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