跟读练习: How To Clear Icy Roads, With Science - 通过视频学习英语口语

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Navigating an icy road can be pretty dangerous.

And while applying a coating of salt is the time -tested method for rendering a frozen highway drivable, that salt has major downsides.

It's toxic for plants, wildlife, and freshwater ecosystems.

It contaminates our drinking water and air quality.

It can even damage our cars, which feels a bit counterproductive.

So how do we make winter roads safe for both drivers and the environment?

Well, science says we have options.

Salting a road is by far the most common de -icing technique.

When salt mixes with water, the resulting solution has a lower freezing temperature than water by itself.

However, this is true for all kinds of solutions, not just salty ones.

Thanks to a scientific principle called freezing point depression,

the temperature at which plain H2O freezes is always higher than its freezing point when something is dissolved into it.

Essentially, the salt keeps water molecules from forming solid ice crystals because the salt interrupts the watery ice structure.

The temperature at which the salty water eventually freezes depends on how salty the solution is.

And although salting roads with the classic sodium chloride is effective, it wreaks havoc on plants and wildlife, contributes to poor air, soil,

and water quality, ruins infrastructure like water treatment plants and bridges, and corrodes our stuff, like the steel in cars.

Which is why some places are experimenting with a few solutions to this chili conundrum.

We can start simple.

Even a different kind of salt can make a difference.

The sodium chloride you put on your food is chemically the same as the rock salt

or halite that's spread on roads to melt ice.

It's cheap, effective, and the infrastructure for delivering it to roads is already in place.

The problem is that the chlorides in the sodium chloride don't ever break down in the environment.

But other salts are better for the environment, if only

because less is required in solution to achieve the same freezing point depression we get with a higher concentration of sodium chloride.

Remember, a salt is just any compound that has positive and negative ions, which together make a neutral charge.

There are a lot of options for what salts you can use.

For instance, magnesium chloride and calcium chloride lower the freezing point more effectively due to some interesting chemistry.

When sodium chloride dissolves in water, it dissociates into two ions, Na -plus and Cl -minus.

Magnesium chloride and calcium chloride, on the other hand,

dissociate into three ions each since they're each made of three total atoms instead of the two in NaCl. And

because the number of dissolved particles in a solution is what determines how low the freezing point of a solution can get,

salts like calcium chloride can do the same job as sodium chloride while using less raw salt to do it.

Some states like Connecticut have used magnesium chloride salts for de -icing, citing the lower cost of the solution.

However, there is a downside.

They're still somewhat corrosive to cars, making them less than ideal.

And these salts are also bad for the environment when they accumulate.

It just doesn't happen as fast as with sodium chloride, because less is needed to do the job.

Figuring out which ions react with what can be a major chemistry puzzle.

And you can find more of those at Brilliant, the online learning platform with thousands of lessons in science,

computer science, and math, and the sponsor for this video.

Their Chemistry and Biology Puzzles course takes interactive learning to the next level, with 28 quick lessons full of puzzles that keep you engaged.

Some of those puzzles cover the basics of chemical reactions

that can help you follow along with all of the ions I just rattled off,

while others pose environmental questions for things like finding a cleaner burning fuel.

You can try them all for free for 30 days at brilliant .org slash scishow, or by clicking the link in the description down below.

That link also gives you 20 % off an annual premium Brilliant subscription.

So, if your ears perked up at the mere mention of the environment, just wait until you hear about this next de -icing alternative.

Of course, there are other options beyond salts for de -icing roads.

Some state road agencies have tested all kinds of weird stuff.

– cheese brine, pickle juice, beet juice, and… pig pee, to name a few?

Welcome to the wild world of potentially eco -friendly methods for melting road ice.

Byproducts from vodka distilleries or sugar beet processing facilities contain a lot of sugars, which, when added to road salts,

helps lower the melting point of the ice, meaning the salt will work better at even lower temperatures.

But not all eco -options are created equal.

For instance, some communities have complained about the smell from that beet wastewater,

water, and some research shows that distillery byproducts can also cause some of those ecosystem problems that we're trying to avoid.

Urea is also marketed as an eco -friendly solution to road salt,

since it's also water -soluble and makes a solution with a lower freezing point than pure water.

And while urea is great at de -icing and is generally safe for pets and children to be around, there are some downsides.

It doesn't perform well below negative 4 degrees Celsius, and once it gets into a waterway, it decreases dissolved oxygen and causes algal blooms.

Plus, urea is actually somewhat expensive, at least compared to the other options out there.

Still, there's definitely a market for more of these less harmful options for de -icing.

The other way to help de -ice our roads is also the way to make pickles.

Brine.

But I'm not talking about your leftover pickle juice.

Brine is just water that's got a lot of salts dissolved in it.

And using brine on the roads is a pretty neat way to prevent the ice from forming in the first place.

When you de -ice a road that's already been snowed upon,

transportation agencies use wet rock salt to break the bond between the ice and the road, making it safer to drive.

But the idea behind the brine is to apply liquid salt to the road ahead of time.

Some places have started brining the roads with liquid salt solution before the snow or ice shows up.

This limits the amount of ice that can form on the road to begin with, and uses about a quarter of the salt of de -icing.

Brining requires a lot of infrastructure and planning.

A community needs trucks with big tanks and pumps to spray the brine onto the pavement's surface.

This stuff can be expensive.

However, communities that have invested in brining roads have reported reducing the overall cost of maintaining winter roads,

even after accounting for the extra equipment and staffing.

And the reason for the savings is simple, they're just not buying as much salt.

So, while nothing is perfect, there are absolutely some ways we can move ahead on making our roads safer and more eco -friendly.

Let's just hope they don't all smell like pig pee.

Thanks for watching.

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本课的词汇与口语要点

这节口语课以视频“How To Clear Icy Roads, With Science”为素材。视频中反复出现的词有：salt, road, chloride, solution, ice。这段视频共有 60 个句子、1197 个单词可供跟读。讲话部分时长为 6:02。说话人语速较快，每分钟约 198 个词，会出现较多连读和弱读。只有 78% 的单词属于英语最常用的 3,000 词，词汇难度较高。

视频中的重点词汇

视频中 15 个值得学习的单词，附发音和释义：

单词	发音	释义
freeze 动词	/ˈfɹiːz/	凍結 /冻结, 凍 /冻
sodium 名词	/ˈsəʊ.di.əm/	鈉 /钠
ion 名词	/ˈaɪ.ɑn/	離子 /离子
puzzle 名词	/ˈpʌzəl/	謎 /谜, 難題 /难题
infrastructure 名词	/ˈɪnfɹəˌstɹʌkt͡ʃə/	基礎設施 /基础设施
juice 名词	/d͡ʒuːs/	汁, 果汁
chemistry 名词	/ˈkɛm.ɪ.stɹi/	化學 /化学
melt 动词	/mɛlt/	融化, 熔化
calcium 名词	/ˈkælsi.əm/	鈣 /钙
salty 形容词	/ˈsɔlti/	鹹 /咸
downside 名词	/ˈdaʊnˌsaɪd/	負面 /负面, 缺點 /缺点
lesson 名词	/ˈlɛs.ən/	課業 /课业, -課 /-课
liquid 名词	/ˈlɪk.wɪd/	液體 /液体, 液態 /液态
wildlife 名词	/ˈwaɪldlaɪf/	野生動物 /野生动物, 野生生物
ecosystem 名词	/ˈikoʊˌsɪstəm/	生態系 /生态系, 生態系統 /生态系统

视频中出现的短语动词

单词	释义
figure out 动词	弄清楚
show up 动词	露面

视频中的语法

说话人最常用的结构，并附上视频中的原话：

结构	视频中的用法
现在完成时 have/has + 过去分词 — 过去发生但与现在仍有关联的事	have used · have tested · have complained
被动语态 be + 过去分词 — 强调发生了什么，而不是谁做的	is dissolved · is required · is needed

需要注意的发音

说话人用了 9 次缩略和弱读形式，例如 they're, doesn't, don't。请按听到的简短形式来说。

“sh” 和 “zh” 音: essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, subscription /səbˈskɹɪpʃən/, freshwater /ˈfɹɛʃˌwɔːtə(ɹ)/
长单词——注意重音位置: infrastructure /ˈɪnfɹəˌstɹʌkt͡ʃə/, ecosystem /ˈikoʊˌsɪstəm/, essentially /ɪˈsɛnʃəli/, potentially /pəˈtɛnʃ(ə)li/, experiment /ɪkˈspɛɹ.ə.mənt/

中文母语者容易读错的音：

/v/ — 不要读成 /w/，上齿轻触下唇: invest /ɪnˈvɛst/, productive /pɹəˈdʌk.tɪv/, interactive /ˌɪn.tɚˈæk.tɪv/, vodka /ˈvɑdkə/, navigate /ˈnæv.ɪ.ɡeɪt/
词尾辅音 — 要读清楚，后面不要加元音: freeze /ˈfɹiːz/, juice /d͡ʒuːs/, melt /mɛlt/, downside /ˈdaʊnˌsaɪd/, liquid /ˈlɪk.wɪd/
/r/ 和 /l/ 的区别: crystal /ˈkɹɪstəl/, principle /ˈpɹɪn.sɪ.pəl/, neutral /ˈnuː.tɹəl/, harmful /ˈhɑɹmfl̩/, particle /ˈpɑɹtək(ə)l/

如何用这段视频练习

先完整听一遍视频，不要开口，记下不认识的单词。
先用 0.75 倍速逐句跟读，熟练之后再回到正常速度。
录下自己的声音并与原声对比，特别注意 freeze, sodium, ion 这类单词。

什么是跟读法？

跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。

影子跟读法: 阅读完整分步指南 →

跟读练习: How To Clear Icy Roads, With Science - 通过视频学习英语口语

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