정의: A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year and the sidereal year are more exact. The modern calendar year, as reckoned according to the Gregorian calendar, approximates the tropical year by using a system of leap years.
| 핵심 연구 분야 | Safety |
|---|---|
| 주요 연도 | 2020년 |
| 주요 연관 키워드 | melanoma |
| 좋아요 수 | 0 |