假定一个小国开放经济首次使用信用卡，初始时货币均衡。信用卡使家庭节省货币余额而把更多的财富保

持在生息资产上。试讨论在下列情况使用信用卡对于名义货币供给。实际货币供给。中央银行的官方外汇储备和汇率的影响。 a．固定汇率制下； b．弹性汇率制下。 Suppose that a small open economy begins to use credit cards for the first time，starting from monetary equilibrium．The credit card allows house-holds to economize on their money balances andthus to hold more of their wealth in interest—bearing assets．Discuss the effects of the introduction of credit cards on the nominal money supply，the real money supply，official foreign—exchange reserves of the central bank and the exchange rate assuming a．Fixed exchange rates． b．Flexible exchange rates．