Such foreign-exchange operations among G-7 central banks have fallen into disuse in recent years, partly owing to the theory that they do not affect exchange rates except when they change money supplies. But in this case we are talking about an ECB purchase of dollars that would change the euro money supply.
近几年来，G-7央行之间再也没有进行过此类外汇操作，部分是因为，在理论上，除非汇率改变了货币供给，否则它们不会干预汇率。但在这里，我们讨论的是欧洲央行购买可以改变欧元货币供给的美元。欧元供给的增加自然会拉低欧元的价格。促使汇率贬值的货币扩张比没有这一效果的货币扩张更加有效，特别是在无法进一步降低短期利率的情况下（目前就是如此）。