Under normal circumstances, it is not allowed. After all, the floating population has increased in this era, and the ID card inspection is quite strict. Including internet cafes, banks, airports, hotels, tickets and so on. . . You must show your ID card. For some gyms that are not strictly managed, maybe. Secondly, under normal circumstances, you will apply for membership cards and discount cards when you go to the gym. It is always impossible to take someone else's ID card every time!