十万个为什么·科学阅读30篇（9）

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为什么冰能浮在水面上？这为何至关重要？

Unlike most substances, water expands when it freezes, making solid ice about 9% less dense than liquid water.
This unusual behavior comes from hydrogen bonds forming open hexagonal crystals as water cools below 4°C.
Because ice floats, lakes and rivers freeze from the top down, insulating deeper water and preserving aquatic life beneath.
If ice sank, bodies of water would freeze solid from the bottom up, making seasonal thawing nearly impossible.
This density anomaly also drives ocean circulation, as cold, salty water sinks near poles and warmer water rises elsewhere.
Glaciers calve floating icebergs not because they’re heavy, but because their freshwater ice displaces denser seawater.
Even small ponds rely on this principle: fish survive winter only because ice forms a protective thermal barrier.
Engineers consider this property when designing polar vessels, refrigeration systems, and climate models.

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Engineers consider this property when designing polar vessels, refrigeration systems, and climate models. 工程师在设计极地船舶、制冷系统及气候模型时，均需考虑这一特性。
This unusual behavior comes from hydrogen bonds forming open hexagonal crystals as water cools below 4°C. 这种反常现象源于水温降至4°C以下时，氢键形成开放的六方晶体结构。
Glaciers calve floating icebergs not because they’re heavy, but because their freshwater ice displaces denser seawater. 冰川崩解形成浮冰，并非因其重量，而是因淡水冰排开密度更高的海水。

这篇中文题目最接近哪一句？为什么冰能浮在水面上？这为何至关重要？一次学校运动会的通知一份超市购物清单

课文第一句的意思更接近？与大多数物质不同，水结冰时体积膨胀，使固态冰的密度比液态水低约9%。今天学校放假了。请把窗户打开。

这一课主要在讲什么？（看英文标题） Why Ice Floats on Water — And Why That Matters How to cook noodles A maths worksheet

Engineers consider this property when designing polar vessels, refrigeration systems, and climate models.

Engineers consider this property when designing polar vessels, refrigeration systems, and climate models.

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用今天的表达，自己说一句。

例子：Engineers consider this property when designing polar vessels, refrigeration systems, and climate models.