(1) Arabic numerals are more scientific than China numerals, so there is no contradiction between "making foreign things serve China" and Arabic numerals and China numerals.

(2) The problem is that "Chinese proper subset symbol" and "Japanese subset symbol" are the same, and there will be contradictions between them.

(3) Compared with Japanese proper subset symbol, Chinese proper subset symbol is concise and beautiful in both positive and negative situations, while Japanese proper subset symbol is unscientific.

(4) At present, all kinds of mathematical symbol software in computers have "cross symbol ∨" and "union symbol ∨", but there are no "subset symbol" and "proper subset symbol", which is caused by using Japanese mathematical symbols in the current high school mathematics textbooks in Chinese mainland.