다음 문장 중 어법상 옳지 않은 것은?
- ①He is leaving for China next Friday.
- ②The weather has been nasty for half a month.
- ③I have not walked a mile before it began to rain.
- ④I will have read this book four times if I read it once again.
정답 ③
출처: 인사혁신처 공개 기출(공공데이터포털, 이용허락 제한 없음)