1. If we choose to place an order at a competitive price, we can only enter the order quantity, but not the order price. The system will read the latest rival price (if the user buys, the rival price is the selling price1; If it is sold, the opponent's price is 1), and a limit order for this opponent's price is issued. 2. There is another way to place an order for the Ethereum contract, that is, price limit entrustment. If this trading method is adopted, you need to specify the price and quantity of the order yourself. Limit orders can be used for both opening and closing positions.