In earlier decades, countries held dollars because they needed to have a highly liquid and widely accepted currency to bridge the financing gap if their imports exceeded their exports. The obvious candidate for this reserve fund was US Treasury bills.
几十年前，各国持有美元的原因是它们需要高流动性、被广泛接受的货币弥补进口超过出口的差额。显而易见的候选储备资金便是美国国债。