Acquisition of the Korean Imperfective Aspect Markers –ko iss– and –a iss– by Japanese Learners: A Multiple‐Factor Account 論文 Ju‐Yeon Ryu・Kaoru Horie・Yasuhiro Shirai ·2015-08-27 ·『Language Learning』 65(4) pp. 791-823 doi:10.1111/lang.12132