Flurry tracked nearly 3 million active users of eBook apps in July, up from just around half a million in March.

Flurry在七月跟踪了电子书应用程序的300万名活跃用户，而这一数字在三月仅为50万。

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Researchers from the Albert Einstein College of Medicine in New York tracked the health of more than 500 elderly men and women for four-and-a-half years.

纽约艾尔·伯特·爱因斯坦医学院(albert Einstein College of Medicine)的研究人员在四年半时间里跟踪调查了500名以上老年男性和女性的健康状况。

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During totality, the Moon tracked through the northern part of the Earth's dark umbral shadow, so the southern half appeared considerably darker than the northern part.

在月全食的过程中，月亮会经过地球本影的北部，因此月亮下半部分会比上半部分暗一些。

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The strongest tornado, rated a maximum EF5 on the Fujita Tornado Scale, tracked for nearly an hour and a half along a 38-mile path from Chickasha through south Oklahoma City and the suburbs of Bridge Creek, Newcastle, Moore, Midwest City and Del City.

CNN: Oklahoma City area was hammered by EF5 tornado in 1999