Chris Donahue Mina Lee 0002 Percy Liang Enabling Language Models to Fill in the Blanks. 2492-2501 2020 ACL https://doi.org/10.18653/v1/2020.acl-main.225 https://aclanthology.org/2020.acl-main.225/ conf/acl/2020 db/conf/acl/acl2020.html#DonahueLL20