Spot use is often the quotation of raw materials used in industry now. Inventory is the goods stored by enterprises in the early stage and the inventory in the hands of traders, which is often used to judge the price of futures. If the inventory is high and the price increase is limited, it shows that the market demand is not strong. Another situation is that speculators deliberately hoard goods, resulting in a shortage of goods in the market. In this case, the price will go up. However, this situation requires considerable funds to control, and this situation rarely occurs in the market unless it is a monopoly.