This topic involves the subject matter that does not constitute patent infringement. According to Article 70 of the Patent Law, anyone who uses, promises to sell or sells an infringing patented product for production and business purposes without knowing that it was manufactured or sold without the permission of the patentee shall not be liable for compensation, but it still constitutes infringement, so it is wrong. According to Article 69 of the Patent Law, the manufacture, use and import of patented drugs or patented medical devices, and the manufacture and import of patented drugs or patented medical devices for their exclusive use, for the purpose of providing information required for administrative examination and approval, are not regarded as infringement of patent rights, so item B is correct. If the same product has been manufactured before the patent application date, the same method has been used or the necessary preparations have been made for its manufacture and use, and the manufacture and use continue only within the original scope, it is not regarded as patent infringement, so item C is correct. Although the accused infringer added new technical features on the basis of using all the necessary technical features in the patent claim of others, it still belongs to the protection scope of the patent right of others, which constitutes infringement, so item D is wrong. Therefore, the correct option in this question is BC.