A国实行资本控制。一年的贸易顺差为8亿美元。 a．贸易顺差对货币供给有什么影响? b．中央银行如何冲销贸易顺差的货币影响? Country A has capital controls and is running a surplus in its trade balance of$800 million a year． a．Whalt is the effect of the trade surplus on the money supply? b．How can the central bank sterilize the monetary impact of the trade surplus?