【英语时差8,16】水墙形成时会发生什么呢-上（在线收听）

Next time you’re sitting in the tub, try the following experiment. Stand up quickly, being careful not to fall over. The water will slosh over to fill in the place where your body was, and then slosh back in the other direction, and so on. You have created what is called a "standing wave" inside your tub-wave that reverberates between two end-points. The same thing happens in any body of water that has walls to it-such as a lake. Instead of a visible, conspicuous wave, however, lakes can have a completely hidden wave that travels under the surface.