Of course. According to the provisions of Article 22 of the Law of People's Republic of China (PRC) on the Protection of Consumer Rights and Interests, if the commodity price drops, consumers can ask the merchants to settle the account according to the price before the price reduction, or ask for a refund of the price difference. On the third day after buying milk powder, you can negotiate with the merchant and ask for the difference. The price difference refers to the futures price difference of different grades, different delivery months, different commodities and different delivery locations.