How do I know if my invention has been patented?

Hello! The examination and approval of invention patents should go through four stages: 1 and preliminary examination. The patent administration organ shall find out whether the application meets the requirements of the patent law on the form of application. 2. Pre-publicity. After receiving an application for a patent for invention, the Patent Office, after preliminary examination, finds that it meets the requirements, and shall make an announcement after 18 months from the date of application. The patentee may publish his application as soon as possible at the request of the applicant. 3. Substantive review. An application for a patent for invention may, at the request of the applicant, be examined in substance at any time within 3 years from the date of filing; If the applicant fails to request substantive examination within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn. When the Patent Office deems it necessary, it may examine the application for a patent for invention on its own. 4. Announcement of authorization registration. If the application for a patent for invention is rejected after substantive examination, the Patent Office shall make a decision to grant the patent right for invention, issue a patent certificate, and register and announce it at the same time. The invention patent right shall take effect as of the date of announcement. I wonder what stage your invention patent application has entered?