【英语时差8,16】虫子是如何浮在水面的？-上（在线收听）

It’s summertime, and you’re on vacation. You sit beside a quiet pond, fishing, trying to relax, trying to think about nothing at all. You watch the leaves stirring, the water rippling in the sunshine, and the water bugs standing on the surface of the water. There are two things involved in this trick: one is a property of the water, and the other has to do with the bug’s feet. Let’s start with the water. Water molecules naturally stick to each other, due to a strong chemical attraction between the individual molecules. At the pond’s surface, the uppermost water molecules experience this attraction as a strong pull toward each other, and downward from the water beneath them.