跟读练习: This structure feels impossible to move - 通过视频学习英语口语

This is a strange one.

It's Jessen's octahedron, infinitesimally flexible.

What does that mean?

Well, if you think about a structure like this one, if this was perfectly rigid, then there would be no movement at all.

But in the real world, these bars would be a little bit stretchy, which means that I can pull up on this joint.

And if I were to plot the lengthening of this rod against the vertical motion of the joint, it would look like this.

You can't move the joint without stretching the bar.

But what about a structure like this?

The curve flattens out zero movement.

So at the very beginning, it's possible to move that joint without the bar lengthening at all.

But then as soon as the joint does move, the bar will have to lengthen.

A structure like this is infinitesimally flexible, but because it exists in the real world, I can actually flex it.

And it feels like it takes no force to do so until it has traveled some distance.

Whereas with this structure, it feels like I can't move it at all.

It's easy to make an infinitesimally flexible joint.

You just take a straight rod and you put the joint in the middle Similarly,

in three dimensions, a polyhedron will be infinitesimally flexible if one of the vertices is coplanar,

whereas Jessen's polyhedron is able to achieve infinitesimal flexibility without having to resort to coplanar vertices.

When I squeeze it, I can feel air coming out.

And incredibly, that's actually proof that Jessen's polyhedron isn't a true flexible polyhedron.

Robert Connolly discovered the first proper flexible polyhedron in 1977.

It's this monster with 18 faces.

Annelly proved that the volume of a flexible polyhedron doesn't change as the polyhedron flexes.

It's called the bellows conjecture because a polyhedron cannot be used as bellows.

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552 句

本课的词汇与口语要点

这节 C1 级别的口语课以视频“This structure feels impossible to move”为素材。视频中反复出现的词有：polyhedron, flexible, joint, infinitesimally, structure。这段视频共有 24 个句子、307 个单词可供跟读。讲话部分时长为 1:41。说话人语速较快，每分钟约 182 个词，会出现较多连读和弱读。只有 75% 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

视频中最难的 11 个单词，附发音和释义：

单词	发音	释义
polyhedron 名词	/ˌpɒlɪˈhiːdɹən/	多面體 /多面体
lengthen 动词	/ˈlɛŋθən/	加長 /加长
bellows 名词	/ˈbɛl.oʊz/	風箱 /风箱
coplanar 形容词	/kəʊˈpleɪnə(ɹ)/	共面
vertex 名词	/ˈvɝˌtɛks/	頭頂 /头顶
conjecture 名词	/kənˈd͡ʒɛkt͡ʃə/	臆測 /臆测, 推測 /推测
flatten 动词	/ˈflæ.tən/	壓平 /压平, 壓扁 /压扁
octahedron 名词		八面體 /八面体
rigid 形容词	/ˈɹɪd͡ʒ.ɪd/	硬性, 僵硬
squeeze 动词	/skwiːz/	壓榨, 擠壓 /挤压
dimension 名词	/daɪˈmɛn.ʃən/	方面, 特點 /特点

视频中出现的短语动词

单词	发音	释义
come out 动词	/ˌkʌm ˈaʊt/	出, 出來 /出来

需要注意的发音

说话人用了 4 次缩略和弱读形式，例如 can't, doesn't, isn't。请按听到的简短形式来说。

长单词——注意重音位置: polyhedron /ˌpɒlɪˈhiːdɹən/, infinitesimal /ˌɪnfɪnɪˈtɛsɪməl/, flexibility /ˌflɛksɪˈbɪlɪti/

中文母语者容易读错的音：

词尾辅音 — 要读清楚，后面不要加元音: bellows /ˈbɛl.oʊz/, vertex /ˈvɝˌtɛks/, flex /flɛks/, rigid /ˈɹɪd͡ʒ.ɪd/, squeeze /skwiːz/
/r/ 和 /l/ 的区别: polyhedron /ˌpɒlɪˈhiːdɹən/, coplanar /kəʊˈpleɪnə(ɹ)/

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 polyhedron, lengthen, bellows 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: This structure feels impossible to move - 通过视频学习英语口语

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