The Maya poured the chocolate drink back and forth between two containers so that the liquid had a layer of bubbles,or foam.

VOA: special.2010.02.17

I wish the Fed had behaved better they didn't seem to recognize the bubbles that we had in the stock market in the '90s and the housing in the 2000s.

从某种意义上说，我希望,政府没有发现出来,九十年代的股票市场泡沫,和新世纪房地产的泡沫。

耶鲁公开课 - 金融市场课程节选