ProQA: Structural Prompt-based Pre-training for Unified Question Answering Wanjun Zhong author Yifan Gao author Ning Ding author Yujia Qin author Zhiyuan Liu author Ming Zhou author Jiahai Wang author Jian Yin author Nan Duan author 2022-07 text Proceedings of the 2022 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies Marine Carpuat editor Marie-Catherine de Marneffe editor Ivan Vladimir Meza Ruiz editor Association for Computational Linguistics Seattle, United States conference publication zhong-etal-2022-proqa 10.18653/v1/2022.naacl-main.313 https://aclanthology.org/2022.naacl-main.313/ 2022-07 4230 4243