Zhihu can't sign a contract with someone else's ID number. Fraudulent use of another person's identity card or the use of a fraudulent identity card violates Article 17 of the National Identity Card Law of People's Republic of China (PRC). The public security organ shall impose a fine of not less than 200 yuan but not more than 1,000 yuan, or detain him for not more than 10 days. If there are illegal gains, the illegal gains shall be confiscated.