A popular answer, for example, when Americans buy your goods in dollars, they first use the dollars to find a bank in China to change them into RMB and pay you, while the dollars are kept in the bank, so you can't use them in China. Remember, your commodity is also RMB, but it represents different forms, such as gold. In this way, in order to maintain the total amount of money in circulation, it is necessary to issue additional shares. If you take the reserve, you will still reduce the currency in circulation, and the reserve is not for this purpose.