legal ground
patent law of the people's republic of china
Article 35 Within 3 years from the date of filing, the administrative department for patent in the State Council may, upon the request of the applicant at any time, make a substantive examination of the application; If the applicant fails to request substantive examination within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn. The patent administrative department of the State Council may, when it deems it necessary, examine the application for a patent for invention on its own.