Before you return to China, tell RBC that you will use your credit card in China and tell them how long you will stay in China, so that they won't stop your card for fear that someone will steal it. After domestic use, RBC will be converted into Canadian dollars according to the foreign exchange rate of the day, and you still have to pay back Canadian dollars. It is best not to use foreign cards in China, because you need to charge exchange rate conversion fees to use foreign cards, so it is better to use RMB.