Fair use refers to the non-commercial use of works published by others under the circumstances clearly stipulated by law, without the permission of the copyright owner, and without having to pay remuneration to them. "Laws expressly stipulated by the law" mainly include? (1) For the purpose of personal study, research, or appreciation, the works published by others have been used; (2) The works published have been performed free of charge; Copy, paint, photograph and record art works; (4) Translate published works created in Chinese language into minority languages ​​and publish them. According to the above regulations, the following are fair use? ['A sang a unpublished song at the class party.', 'B translated an English work into a Mongolian work and published it.', 'Company C produced the sculptures in public squares and released them as pictures.', 'In order to write a paper, Deng copied the papers published by Geng for reference.']