Futures: Futures are relative to the spot. Spot is cash spot, that is, you take 100 yuan to the fruit farmer to buy 50 kilograms of apples; Futures are contract transactions, and contracts can be transferred to each other. To put it bluntly, you sign an acquisition contract with the fruit grower, and the contract stipulates that after half a year, you will buy 50 kilograms of apples from the fruit grower with 100 yuan. The purpose of futures is to hedge the uncertain risks in the future. If the apple sells 50kg 150 yuan for half a year, you will be profitable. Which contract signed six months ago made you pay 50 yuan less?

National debt: refers to the government borrowing money from investors, agreeing on the repayment period and paying certain interest at the same time.