l Commodity spread refers to the price difference between the same product due to different circulation links, purchase and sales regions, purchase and sales seasons, and different quality. Which of the following are commodity spreads. ['A pound of white radish in spring, and a pound of carrot in summer.', 'Audi cars differ from Alto cars.', '"Political Economics" published by Chunfeng Press is 5 yuan cheaper than a book of the same name published by Qiuyu Press.', 'The salt of A land is cheaper than that of B land because A land.']