Before that the United States went through repeated banking crises when people would start demanding the gold for their notes.

才有了中央银行，在这之前,当人们向银行索要金子来兑现他们的纸币时,美国经历了一次又一次的重蹈覆辙的银行业危机。

耶鲁公开课 - 金融市场课程节选