这种震动以前被诟病为60年周期性日长变化的原因，但该研究发现的自转速度表明，它并不是罪魁祸首，英国利兹大学的乔恩芒德说。

The twisting had previously been blamed for a 60-year cycle in day length, but the rate of rotation found in this study suggests it is not the culprit, says Jon Mound at the University of Leeds, UK.

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据估计增长率可达6.1 %，原因是2001 - 02年增速放缓以来已出现强劲周期性回升以及各地区普遍呈现增长强势。

Growth is estimated to be 6.1 percent, due to a strong cyclical global rebound from the 2001-02 slowdown and a solid performance spanning all regions.

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其中有自然原因：2006年以来，加州一直处于一个周期性干旱中，而气候变化是对州内山区积雪的长期威胁。

Some of the reasons are natural; California has been in one of its periodic droughts since 2006, and climate change is a long-term threat to the state's mountain snowpacks.

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