The U.S. dollar part of the credit card is mainly used in specific scenarios, mainly in the following aspects:

1. Use abroad: When traveling or shopping overseas, you can directly use the U.S. dollar part of the credit card. When using a US dollar account to make purchases by card, no additional currency conversion is required, which is convenient and fast.

2. International website transactions: If you plan to shop on international websites that support U.S. dollar payments, U.S. dollar credit cards can also come in handy for online transactions.

However, in China, the use of US dollar accounts is restricted, and it is not possible to overdraft or directly use the account balance domestically. Repayments usually need to be made through foreign currency transactions or linked RMB accounts. For example, if you consume through UnionPay lines, the transaction amount will be automatically converted into RMB for accounting without any handling fee. However, non-UnionPay lines may incur a foreign exchange handling fee of about 1.5%.

You need to pay attention when repaying. The debt in the foreign currency account of the credit card usually needs to be manually linked to the appropriate RMB or foreign currency account for repayment. China Merchants Bank provides two methods: "foreign currency to foreign currency" and "RMB to foreign currency". When choosing, you need to clear the priority to avoid unexpected repayment sequences due to automatic operations. Pudong Development International Card gives priority to repaying RMB debts. Therefore, when using the dollar portion of your credit card, you need to understand and manage these rules appropriately to avoid additional fees and repayment worries.