英語時差:蟲子是如何浮在水面的？-下

00:00

00:00

MP3下載 文本下載

https://online2.tingclass.net/lesson/shi0529/10000/10183/1052.mp3

https://image.tingclass.net/statics/js/2012

 This creates what’s called "surface tension"-a somewhat compressed layer of water molecules right at the pond’s surface. You can think of this layer as being like a tight film over the surface of the pond. How does this help the water bug? If the surface water stuck to its feet as well as it stuck to the water below, the bug would be pulled under. As it turns out, the bug’s feet are covered with waxy hairs that are "hydrophobic"-which means they chemically resist contact with water. This combination of strong surface tension and water-resistant feet is what lets our bug stand on the water, without even getting wet!