None of the banks you mentioned can short. Only China Bank in Shanghai has margin foreign exchange business, and Bank of China in other regions does not. When trading on the Internet, these banks can trade 24 hours a day and entrust stop-loss orders. The transaction fees are spread, and the spread of banks in different places is different, which is not uniform. Generally, the spread of firm trading is around 3 points, and the margin is around 1 points.