Since the 20th century, with the continuous deepening of economic research and the expansion of economic activities worldwide, different understandings of the concept of capital have been used. One is to continue to use "capital" as one of the political economies The concept of class attributes is used to study the movement of capitalism; one is to use capital as a natural attribute concept in commodity economics, that is, a simple economic concept, to study the objective economic law of "money produces more money" The latter is called the modern capital concept. It can be seen from this passage that what is the concept of "capital" in the 20th century? ['Expanding political economy concepts.', 'Class attributes give way to pure economic concepts.', 'The concept of modern capital worldwide.', 'Concept of class attributes and natural attributes.']