请你把中文翻译成为英文
负利率政策是中央银行采用的一种非常规货币政策工具，其名义目标利率设置为负值，低于理论上的零下限。
A negative interest rate policy (NIRP) is an unconventional monetary policy tool whereby nominal target interest rates are set with a negative value, below the theoretical lower bound of zero percent.