十万个为什么·科学阅读30篇（2）

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珊瑚礁如何在没有骨骼或外壳的情况下建造巨大结构？

Coral reefs are built by tiny animals called polyps that live in colonies underwater.
Each polyp secretes a hard external skeleton made of calcium carbonate from seawater minerals.
Over centuries, generations of polyps add layer upon layer, forming massive limestone frameworks.
Algae living inside coral tissues provide energy through photosynthesis, fueling this growth process.
Water temperature, light, and low nutrient levels must stay within narrow ranges for reefs to thrive.
When stressed by warming or pollution, corals expel their algae and bleach, halting construction.
Reef growth rates vary from 0.3 to 10 centimeters per year depending on species and conditions.
Some reefs, like Australia’s Great Barrier Reef, are over 20 million years old and span 2,300 kilometers.
Unlike shells or bones, coral skeletons are not part of the animal’s body but external deposits.
This collective, slow-building strategy makes reefs the largest biological structures visible from space.

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Over centuries, generations of polyps add layer upon layer, forming massive limestone frameworks. 历经数百年，一代代珊瑚虫层层堆积，形成巨大的石灰岩骨架。
Algae living inside coral tissues provide energy through photosynthesis, fueling this growth process. 生活在珊瑚组织内的藻类通过光合作用提供能量，驱动这一生长过程。
This collective, slow-building strategy makes reefs the largest biological structures visible from space. 这种集体性、缓慢累积的建造方式，使珊瑚礁成为太空中可见的最大生物结构。

这篇中文题目最接近哪一句？珊瑚礁如何在没有骨骼或外壳的情况下建造巨大结构？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？珊瑚礁由生活在水下群落中的微小动物——珊瑚虫建造。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） How Do Coral Reefs Build Massive Structures Without Any Bones or Shells? How to cook noodles A maths worksheet

Coral reefs are built by tiny animals called polyps that live in colonies underwater.

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Over centuries, generations of polyps add layer upon layer, forming massive limestone frameworks.

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用今天的表达，自己说一句。

例子：Coral reefs are built by tiny animals called polyps that live in colonies underwater.