日晷

例句：

1. 1. The ancient Romans used a sundial to measure the length of days and months.
   古罗马人使用日晷来测量天数和月份的长度。
2. 2. In medieval times, people often used hourglasses to keep track of time during long nights.
   中世纪时期，人们经常使用沙漏来在漫长的夜晚中跟踪时间。
3. 3. Our school has an old sundial in the courtyard, which is still used for teaching students about timekeeping.
   我们学校有一个旧的日晷在庭院里，仍然被用来教授学生关于计时的知识。