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为什么先看到闪电，几秒后才听到雷声？

Light travels nearly a million times faster than sound—about 300,000 km per second versus 343 m per second.
Because lightning and thunder happen simultaneously, the delay tells us how far away the storm is.
Counting seconds between flash and bang and dividing by three gives distance in kilometers.
Sound bends and scatters as it passes through varying air temperatures and wind layers, causing rumbling.
Nearby strikes produce sharp, loud cracks; distant ones sound like low, rolling booms.
Temperature gradients in the atmosphere can refract sound waves, making thunder audible farther than expected.
Mountains or buildings may echo thunder, stretching it out or creating multiple arrival points.
Thunder cannot travel through vacuum—so no sound occurs on the Moon, even during lightning-like discharges.
Meteorologists combine lightning maps with thunder timing to triangulate storm cell movement and intensity.
Wearing headphones during storms won’t mute thunder—it’s the pressure wave itself vibrating your eardrums.

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

Nearby strikes produce sharp, loud cracks; distant ones sound like low, rolling booms. 近距离雷击发出尖锐响亮的爆裂声；远处雷击则听起来像低沉滚动的轰鸣。
Counting seconds between flash and bang and dividing by three gives distance in kilometers. 用闪电与雷声之间的秒数除以3，即可得出距离（单位：公里）。
Mountains or buildings may echo thunder, stretching it out or creating multiple arrival points. 山体或建筑物可能反射雷声，使其拉长或产生多个到达点。

这篇中文题目最接近哪一句？为什么先看到闪电，几秒后才听到雷声？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？光速约为每秒30万公里，比声速（约每秒343米）快近百万倍。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 We Hear Thunder Several Seconds After Seeing Lightning? How to cook noodles A maths worksheet

Nearby strikes produce sharp, loud cracks; distant ones sound like low, rolling booms.

Nearby strikes produce sharp, loud cracks; distant ones sound like low, rolling booms.

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：Nearby strikes produce sharp, loud cracks; distant ones sound like low, rolling booms.