Word~시~siMeaningat the time ofPart of speechpostpositionPronunciationCourseHardcore KoreanLessonLesson 23Usages of ~si여권 복사본은 체크인 시 연락처와 함께 제출해야 해요.yeogwon boksaboneun chekeu-in si yeonrakcheowa hamkke jechulhaeya haeyo.You must submit a passport copy along with your contact information at check-in.