The tilt of Earth's axis, toward the Sun at some times of the year and away from the Sun at other times, is responsible for the annual cycle of seasons.

地轴的倾斜在一年中的某些时候朝向太阳，而在其它时间远离太阳，造成了每年的季节循环。

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It can loosely be described as travel that takes place at regular intervals—often in an annual cycle—that may involve many members of a species, and is rewarded only after a long journey.

它可以比较粗略地描述成是发生在固定周期（这个周期通常是一年一次）的包含某一个物种很多成员的集体旅行，并且只有在长途旅行后才有回报。

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The annual cycle repeats itself.

每年的周都会循环。

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Moreover, looking back over 1927-2012, we find only four instances where a particular annual cycle had the best return for two consecutive years.

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Annual cycle of energy balance of Zongo Glacier, Cordillera Real, Bolivia.

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"Seymour's work provided evidence with which to propose and eventually launch the Cryosat mission, which is now - as his last paper describes - providing the first observations of the annual cycle of sea-ice growth and decay throughout the Arctic Ocean, " Dr Giles said.

BBC: Cryosat spots Arctic sea-ice loss in autumn