十万个为什么·科学阅读30篇（2）

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为什么冰能浮在水面上，而大多数固体却沉入自己的液体中？

Water expands when it freezes, making ice about 9% less dense than liquid water.
This unusual behavior comes from hydrogen bonds forming a hexagonal lattice with open spaces.
Most substances contract on cooling, so their solids sink — but water reaches maximum density at 4°C.
As surface water cools below 4°C, it becomes less dense and rises, eventually freezing on top.
This layer of ice insulates lakes and rivers, allowing aquatic life to survive winter below.
Without this property, freshwater ecosystems would freeze solid from the bottom up.
The density anomaly also affects ocean circulation and global climate regulation.
Scientists study ice structure to improve materials for cold-weather engineering and cryopreservation.
Even tiny impurities or pressure can shift freezing points and crystal shapes slightly.
This single molecular quirk supports life on Earth in ways few other elements can match.

听 → 读 → 学表达 → 懂 → 今天会说这一句 → 跟读录音 → 自己说一句。

The density anomaly also affects ocean circulation and global climate regulation. 密度异常还影响海洋环流与全球气候调节。
Without this property, freshwater ecosystems would freeze solid from the bottom up. 若无此特性，淡水生态系统将自底部向上完全冻结。
Scientists study ice structure to improve materials for cold-weather engineering and cryopreservation. 科学家研究冰的结构，以改进寒冷环境工程和低温保存材料。

这篇中文题目最接近哪一句？为什么冰能浮在水面上，而大多数固体却沉入自己的液体中？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？水结冰时体积膨胀，使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 Does Ice Float on Water While Most Solids Sink in Their Liquids? How to cook noodles A maths worksheet

The density anomaly also affects ocean circulation and global climate regulation.

The density anomaly also affects ocean circulation and global climate regulation.

第一版：录下来、回听、再听标准音。系统打分以后再加。

用今天的表达，自己说一句。

例子：The density anomaly also affects ocean circulation and global climate regulation.