十万个为什么·科学阅读30篇（1）

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为什么有些树秋天落叶，有些却常青？

Deciduous trees—like maples and oaks—shed leaves each fall to conserve water during cold, dry winters.
They form a special corky layer at the base of each leaf stem, cutting off water and nutrient flow gradually.
Chlorophyll breaks down first, revealing yellow and orange pigments that were always present but hidden.
Red anthocyanins are newly made in autumn, possibly protecting leaves while nutrients are reabsorbed.
Evergreen trees—such as pines and spruces—keep needles year-round because their waxy coating and antifreeze compounds prevent freezing damage.
Their needles have fewer pores and thicker cell walls, reducing water loss even in freezing winds.
This adaptation lets evergreens photosynthesize whenever temperatures rise above freezing—even in winter.
Foresters consider leaf-shedding patterns when selecting tree species for urban planting in changing climates.

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

This adaptation lets evergreens photosynthesize whenever temperatures rise above freezing—even in winter. 这种适应性使常绿树只要气温升至冰点以上——哪怕在冬季——就能进行光合作用。
Red anthocyanins are newly made in autumn, possibly protecting leaves while nutrients are reabsorbed. 红色花青素则在秋季新合成，可能在养分被重新吸收时保护叶片。
Foresters consider leaf-shedding patterns when selecting tree species for urban planting in changing climates. 林务人员在气候变化背景下选择城市绿化树种时，会考虑树木的落叶模式。

这篇中文题目最接近哪一句？为什么有些树秋天落叶，有些却常青？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？落叶树（如枫树和橡树）每年秋季落叶，以在寒冷干燥的冬季节约水分。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 Some Trees Lose Leaves in Autumn While Others Stay Green? How to cook noodles A maths worksheet

This adaptation lets evergreens photosynthesize whenever temperatures rise above freezing—even in winter.

This adaptation lets evergreens photosynthesize whenever temperatures rise above freezing—even in winter.

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 adaptation lets evergreens photosynthesize whenever temperatures rise above freezing—even in winter.