A line drawn on a map linking points at a particular height above sea level (i.e. a contour line) but that lie on surfaces formed at sea level at a specified time in the past.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。