[9급 지방직 영어 2024년 6번]

밑줄 친 부분 중 어법상 옳지 않은 것은?
One of the many ① virtues of the book you are reading ② is that it provides an entry point into Maps of Meaning, ③ which is a highly complex work ④ because of the author was working out his approach to psychology as he wrote it.
영어
정답 ④

출처: 인사혁신처 공개 기출(공공데이터포털, 이용허락 제한 없음)