Short selling means borrowing goods and selling them to others. Current market price 100 yuan, and then take cash. If the commodity price falls to 50 yuan after one year, you can buy it back and return it, so you can earn 50 yuan. If after one year, the goods go up to 200 yuan instead of falling, and you spend 200 yuan to buy them and return them, then you will lose 100 yuan. This is the basic principle of short selling for profit.