Saku Sugawara Yusuke Kido Hikaru Yokono Akiko Aizawa Evaluation Metrics for Machine Reading Comprehension: Prerequisite Skills and Readability. 806-817 2017 ACL (1) https://doi.org/10.18653/v1/P17-1075 conf/acl/2017-1 db/conf/acl/acl2017-1.html#SugawaraKYA17