美联储前主席格林斯潘最近说他现在认为投机泡沫是我们经济的重要驱动力，但是与此同时世界各国的货币主管部门无法控制泡沫。
Alan Greenspan, the former Fed chairman, recently said that he now believes that speculative bubbles are important driving forces in our economy, but that, at the same time, the world’s monetary authorities cannot control bubbles.