When commodity prices rise, the demand for substitutes will definitely increase. When the price of substitutes rises, the demand for goods will increase.

Complement: Two commodities * * * satisfy one desire.

If the two commodities are complementary, if the price of one commodity rises, its demand will decrease, and the demand for its complementary commodities will also decrease; On the contrary, the price of a commodity drops, the demand increases, and at the same time the demand for its supplementary commodities increases. Two or more complementary commodities are related commodities that satisfy consumers' same desire. If consumers' hobbies, monetary income and other commodity prices remain unchanged, and if the price drop of commodity A leads to an increase in demand for commodity B, then commodities A and B are complementary commodities.

In layman's terms, complementary goods mean that if two kinds of goods must be combined to meet people's needs, then these two things are complementary goods.

Therefore, the increase in the price of supplementary commodities leads to a decrease in the demand for this commodity.