科学为什么·英语30篇（1）

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为什么某些蚌类仅在沙粒进入壳内后才产珍珠？

Pearls form when an irritant like sand or a parasite slips between a clam’s mantle and its shell.
The mollusk cannot remove the particle, so it coats it with layers of nacre over months or years.
Nacre is the same iridescent material that lines the inner shell and gives pearls their soft glow.
Not all clams make pearls—only those with glands capable of secreting abundant, uniform nacre.
Saltwater oysters and freshwater mussels are the most common pearl producers in nature.
The shape and color of a pearl depend on the irritant’s size, shape, and the mollusk’s health.
Some pearls are round because the grain rotates slowly inside the mantle tissue.
Others stay baroque if the particle remains fixed or gets coated unevenly.
Farmers now insert polished beads deliberately to control pearl shape and quality.
Still, natural pearls remain rare because the process requires perfect biological timing and environment.

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

Others stay baroque if the particle remains fixed or gets coated unevenly. 若微粒固定不动或包裹不均，则形成不规则的巴洛克式珍珠。
Farmers now insert polished beads deliberately to control pearl shape and quality. 如今养殖者会主动植入抛光珠核，以控制珍珠的形状与品质。
Saltwater oysters and freshwater mussels are the most common pearl producers in nature. 海水牡蛎和淡水贻贝是自然界中最常见的珍珠生产者。

这篇中文题目最接近哪一句？为什么某些蚌类仅在沙粒进入壳内后才产珍珠？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？当沙粒或寄生虫等异物进入蚌的外套膜与贝壳之间时，珍珠便由此形成。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 Do Certain Clams Produce Pearls Only After a Grain of Sand Enters Their Shell? How to cook noodles A maths worksheet

Others stay baroque if the particle remains fixed or gets coated unevenly.

Others stay baroque if the particle remains fixed or gets coated unevenly.

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：Others stay baroque if the particle remains fixed or gets coated unevenly.