名词
中文翻译：极夜
同义词：
['polar day', 'polar daylight']
例句：
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1. The polar night is thelongest period of darkness in the year.
极夜是一年中最长的黑暗时期。
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2. Duringthe polar night, the sun never sets.
在极夜期间，太阳从不落下。
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3.Polar nights are a natural phenomenon thatoccurs only during certain seasons.
极夜是一种只在特定季节出现的自然现象。