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【简答题】
如图，长为4cm，宽为3cm的长方形木板，在桌面上做无滑动的翻滚（顺时针方向）木板上点A位置变化为 ，其中第二次翻滚被桌面上一小木块挡住，使木板与桌面成30°角，则点A翻滚到A 2 位置时共走过的路径长为 cm．（结果保留π）
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B.
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which
B.
as
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that
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what
【单选题】The two Harvard economists note in their study that, for much of the 20th century,
A.
enrollment kept decreasing in virtually all American colleges and universities
B.
the labor market preferred high-school graduates to college graduates
C.
competition for university admissions was far more fierce than today
D.
the gap between the earnings of college and high-school graduates narrowed
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