Studies in countries such as Ghana and Cameroon suggest many girls at secondary school miss a week of classes when they have their period, or drop out altogether when they reach puberty.

在加纳和喀麦隆等国家开展的研究显示，许多女中学生在例假期间一个星期不去上学，当她们进入青春期，有的甚至辍了学。

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Isotopes of carbon in tree rings and beryllium in ice cores show a drop-off in solar radiation during much of the period.

树木年轮的碳同位素和冰核中钚同位素的检测都显示出在上述阶段的大多数时间内太阳辐射能量出现下降。

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The temperature drop during the Cretaceous period would almost certainly have wiped out an 'abundance' of the world's dinosaurs.

曾经称霸地球显赫一时的恐龙，在白垩纪时代的这次温度巨变中，似乎全都灭绝了。

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According to the Commerce Department, foreign direct investment in the U.S. did indeed drop for a period after 2001, but has generally been on the rise since 2003, increasing 67% in 2006.

FORBES: The Insourcing 50

As for defense spending despite the big (annualized) Q4 drop from the prior period, 2012 defense spending was higher than 2008.

FORBES: Q4 Growth and the Sequester

The bearish percentage has seen a 12% drop during the same period.

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