The knowledge point examined in this question is compulsory licensing of patent implementation. According to Article 48 of the Patent Law, under any of the following circumstances, the administrative department for patent in the State Council may grant a compulsory license to exploit a patent for invention or utility model upon the application of a unit or individual with the conditions for implementation: (1) The patentee has not exploited or fully exploited his patent for three years from the date of granting the patent right, and for four years from the date of filing the patent application, without justifiable reasons; (2) The patentee's act of exercising the patent right is recognized as a monopolistic act according to law, in order to eliminate or reduce the adverse impact of the act on competition. According to Article 49 of the Patent Law, in case of national emergency or extraordinary circumstances, or for the purpose of public interests, the patent administration department of the State Council may grant compulsory license to exploit the invention patent or utility model patent. According to Article 5 of the Patent Law, for the purpose of public health, the patent administration department in the State Council may grant compulsory license for the manufacture and export of patented drugs to countries or regions that meet the requirements of relevant international treaties to which the People's Republic of China is a party. According to Article 51 of the Patent Law, if a patented invention or utility model is a significant technological progress with significant economic significance compared with the previously patented invention or utility model, and its implementation depends on the implementation of the previous invention or utility model, the patent administration department in the State Council may grant a compulsory license to exploit the previous invention or utility model upon the application of the latter patentee. Therefore, the correct answer is ABD.