他们最有说服力的抱怨就是人们对量化宽松究竟如何运作知之甚少，因此美联储冒着可能毁灭全球金融系统的巨大风险换来的只是对美国经济的一点推动作用。
Their most telling complaint is that too little is known about how quantitative easing works, and that the Fed is therefore taking undue risks with the global financial system to achieve a modest juicing of the US economy.