十万个为什么·科学启蒙30篇（4）

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为什么蜂蜜几乎不变质

Honey has very low water content, usually below 18%, which prevents most microbes from growing.
Its high sugar concentration creates osmotic pressure that pulls water out of bacterial cells.
Bees add an enzyme called glucose oxidase to nectar, which produces hydrogen peroxide slowly.
This mild antiseptic compound inhibits microbial growth without harming humans.
Honey is also naturally acidic, with a pH between 3.2 and 4.5, too low for many pathogens.
Even ancient honey found in Egyptian tombs remained edible after thousands of years.
Crystallization doesn’t mean spoilage—it’s just glucose forming solid particles over time.
Storing honey in airtight containers keeps moisture out and preserves its stability.
Unlike fruit juices or milk, honey lacks nutrients that fast-growing bacteria need.
Modern food scientists use honey’s preservation traits to develop natural food preservatives.

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

This mild antiseptic compound inhibits microbial growth without harming humans. 这种温和的抗菌成分能抑制微生物生长， yet 对人体无害。
Crystallization doesn’t mean spoilage—it’s just glucose forming solid particles over time. 结晶并非变质，只是葡萄糖随时间推移析出形成固体颗粒。
Storing honey in airtight containers keeps moisture out and preserves its stability. 将蜂蜜存于密封容器中可隔绝水分，保持其稳定性。

这篇中文题目最接近哪一句？为什么蜂蜜几乎不变质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？蜂蜜含水量极低，通常低于18%，能抑制大多数微生物生长。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 Honey Resists Spoilage Almost Indefinitely How to cook noodles A maths worksheet

This mild antiseptic compound inhibits microbial growth without harming humans.

This mild antiseptic compound inhibits microbial growth without harming humans.

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：This mild antiseptic compound inhibits microbial growth without harming humans.