2. Early morning, also called late night, refers to a period of time from midnight to before dawn, about 00: 00-06: 00.

Morning refers to the period from midnight to noon, and also refers to the period from early morning to noon.

4. It can be seen that the early morning is an inclusive relationship within the time range of the morning.

Early morning is of special significance in medicine, mainly because this time period is closely related to physiological rhythm.

6. When the morning comes, that is, after entering the zero point, most of the normal physiological activities of the human body will be weakened, and then some physiological characteristics that are not available during the day will be displayed.

7. Ten-hour time system in ancient times: the early calendar and time used decimal system.

8. The five-element calendar of Yin and Yang belongs to the October solar calendar.

9. The ten-hour system is the decimal division of time.

10. At the initial stage of using ten o'clock, some key natural phenomena, biological reflex and living habits are selected as time nodes to help people know the time.

1 1. Later, it was gradually changed to be represented by numbers or heavenly stems.

12. According to Tian Wenzhi, the five time nodes in the daytime are: Chao, Yu, Zhong and Yihe.

13. The five time nodes at night are: A, B, C, D and E.

14. The five time nodes at night gradually changed into additional time service nodes during night security patrol, which were called five drums and five watches and lasted until the late Qing Dynasty.

15. centimeter system: the centimeter system is a further division of the ten-hour system, that is, the ten-hour system is further divided into a balanced hundred-hour system.

16. Engraving may have originated in Shang Dynasty, and there are unearthed sundials in Han Dynasty. The scale on the disc is 69 carvings that may be used for carving.

17. On the other hand, people's demand for timing accuracy and the proposal of 100 seconds have promoted the occurrence of copper pot dripping.

18. Twelve-hour system: Since the Western Zhou Dynasty, the China calendar has gradually stabilized the concept of twelve months a year.

19. When a day is compared to a year, a day is also divided by twelve o'clock, and the date demarcation point (date change point) is fixed at midnight.

20. Twelve time nodes (starting points) at twelve o'clock are twelve o'clock.

2 1. The names of the Han Dynasty are Midnight, Crow, Pingdan, Sunrise, Food Time, Corner, Japan-China, Sundial, Dawn, Dusk, and Human Decision.

22. With the diversification of people's work and life, they can't express themselves gradually, so they use twelve branches to express themselves, including eleven o'clock in the evening, one o'clock in the morning, three o'clock in the morning, five o'clock in the morning, seven o'clock in the morning, nine o'clock in the morning, eleven o'clock in the afternoon, one o'clock in the afternoon, three o'clock in the afternoon, five o'clock in the evening and seven o'clock in the evening.