那些夜晚十分清静，空气清凉、繁星点点。

The nights were pure with cold air and lit with stars.

《柯林斯英汉双解大词典》

科学家研究发现，当人的大脑开始出现过热时，打呵欠的动作就充当天然的“自动调温器”，让清凉的空气进入大脑，使大脑温度恢复到健康水平。

When the head begins to heat up, yawning acts as a natural "thermostat" by allowing cool air to rush in and bring the brain back down to a healthy temperature, research suggests.

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这款在床脚位置添加了消音双页扇的床，清凉的空气可以从头的位置进入并在起气垫作用的柔软的薄膜间循环。

Using extremely quiet dual-fans at the end of the bed, cool air is pulled in from behind your head and circulated through the soft membrane which also ACTS as an air-cushion.

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