Selling first and then selling is also called empty. Shorting can be understood this way. You don't have this futures contract. Now the market price is 654.38+ 10,000. Do you think it will fall? You borrow a futures contract from the exchange and sell it to others. When the market price reaches 90,000, and you think it is almost enough, you can buy the contract and return it to the exchange. (This short is hard to understand. ) buying before selling is also called selling more. This is easy to understand. The current market price is 650.