BCD
According to Article 340 of the Contract Law: “For inventions and creations developed through joint cooperation, unless otherwise agreed by the parties, the right to apply for a patent belongs to the jointly developed invention. The parties *** have. If one party transfers its exclusive right to apply for a patent, the other parties shall have priority in the transfer under the same conditions.
The party involved in the cooperative development shall declare that it has waived its right to apply for a patent. * If the applicant has the right to apply for a patent, the other party may apply alone or the other parties may apply jointly. If the applicant obtains the patent right, the party giving up the right to apply for the patent may exploit the patent free of charge. If the applicant agrees to apply for a patent, the other party or other parties may not apply for a patent. "Therefore, item BC is correct and item A is incorrect.
According to Article 342 of the Contract Law: "Technology transfer contracts include transfer of patent rights, transfer of patent application rights, transfer of technical secrets, and patent implementation license contracts. Technology transfer contracts shall be in writing." Item D is correct.