当彗星接近太阳时，它表面的冰壳开始融化分解成大大小小的碎片，大多数碎片并不会比沙粒更大。
When a comet gets close to the sun, melting ice releases pieces of dust, most no larger than grains of sand.
波斯人发现不会让冰融化的储存方法。
The Persians discovered how to store ice so that it would not melt.
波斯人发现不会让冰融化的储存方法。
The Persians discovered how to store ice so that it would not melt.
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