听力文本

Insects seem irresistibly drawn towards the source and then get trapped by the sticky lines.
昆虫总是禁不住光源的诱惑，结果就被这些粘乎乎的丝拿住了
Once stuck, there is no escape.
一旦被粘住，根本没有脱逃的机会。
Now it's just a matter of reeling in the line and slowly consuming the catch alive.
现在，它只需收起丝线，然后慢慢吃掉尚且活着的猎物。
By ensnaring the insects that hatch in this cave,
通过诱捕洞穴内羽化的昆虫
these glow-worms have solved the biggest challenge
这些萤火虫成功地解决了终生穴居动物面临的最大难题
that permanent cave-dwellers face, finding a regular and reliable source of food.
即找到长期而可靠的食物资源

One kind of rock makes this whole underground world possible, limestone.
这些地底世界之所以会存在，都是因为一种岩石，石灰岩。
Most of the world's caves are found within it and it covers nearly 10% of the Earth's surface.
世界上大部分洞穴内都存在石灰岩，它覆盖了地球表面将近10%的面积。
Limestone is composed of minerals derived from marine shells and corals.
石灰岩由海螺和珊瑚中的矿物沉积后形成
So although this rocky escarpment in the United States
所以，尽管美国境内的这座石壁，
is now hundreds of metres above sea level, it was actually formed underwater.
如今矗立在海平面以上几百米高的地方，它实际上却是在水下形成的。

词汇解析

1.be composed of 由……组成
Regardless of the type of business you own, your work will be composed of those three items.
无论你从事什么类型的行业，你所有的工作都由这三项组成。

2.derive from 来自
Thousands of English words are derived from Latin.
数以千计的英语词汇源自拉丁语。

视频及简介

洞穴是不受阳光控制的生物栖息地之一，但这并不意味着那里就不存在野生生物。本集节目将深入洞穴内神秘而永恒的黑暗，探索山洞、洞穴和隧洞中未知的地下世界。