中文版：

银行为什么不换零钱？这可能是许多人的疑惑。当我们需要零钱时，通常会想到去银行兑换。但是，有时候银行可能不会给我们兑换零钱，这让我们感到困惑。

实际上，银行不兑换零钱的原因是因为成本和效益的问题。银行需要确保它们的货币储备充足，以支持各种交易和取款需求。如果银行必须储备大量的零钱，这将会增加银行的成本，因为它们需要更多的存储空间和更多的员工来处理这些零钱。此外，零钱的面值较小，因此银行获得的收益也很小，这使得兑换零钱变得不划算。

另外，银行也可能会受到监管机构的限制。监管机构可能会规定银行兑换零钱的限额或者完全禁止兑换零钱。这些限制可能是出于反洗钱和反恐怖主义融资的考虑，以防止不法分子利用大量兑换零钱来掩盖非法活动。

因此，我们需要理解银行不兑换零钱的背后原因。在需要零钱时，我们可以选择去超市、加油站等地方使用现金购买商品来获得零钱，或者使用电子支付方式来解决这个问题。

英文版：

Why don't banks give change? This may be a question for many people. When we need change, we usually think of going to the bank to exchange it. However, sometimes the bank may not exchange our change, which confuses us.

实际上，the reason why banks do not exchange change is because of cost and efficiency issues. Banks need to ensure that their currency reserves are sufficient to support various transactions and withdrawal needs. If banks must储备大量的change，this will increase the cost to the bank because they need more storage space and more employees to handle these coins. In addition, the face value of coins is small, so the benefit that the bank gains is also small, making it not cost-effective to exchange change.

In addition, banks may also be subject to regulatory restrictions. Regulatory agencies may require banks to limit the amount of change they exchange or prohibit exchanging change entirely. These restrictions may be due to anti-money laundering and anti-terrorism financing considerations to prevent illegal activities by individuals using a large amount of coins to cover up their actions.

Therefore, we need to understand the reasons behind banks not exchanging change. When we need change, we can choose to go to the supermarket, gas station, etc., use cash to buy goods to get coins or use electronic payment methods to solve this problem.