How to judge whether today is a, b, c and d day?

There are 30 days in a month, from 1- 10,1-20 and 2 1-30: A day, B day, C day, D day, E day, Ji day, Geng day and Xin day respectively. A, b and d refer to 1 and 2 days of each month. Of course, these days refer to the lunar calendar.

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Tiangan refers to the ten Tiangan in heavenly stems and earthly branches, which is a traditional word order symbol in China, and can be recycled. There are other names, such as "Yufeng, Youmeng, Rouzhao, Qiangyi, Zhu Yong, Tu Wei, Zhang Shang, Shigemitsu, Xuannuo and Zhaoyang".

The five elements of Tiangan can be divided into yin and yang, specifically: Jiamu, Mu Yi, Huhuo, Ding Huo, Wutu, Jitu, Gengjin, Cynanchum atratum, Renshui and Guishui, in which methyl propargyl alcohol is positive and ethyl butyl hexadecyl is negative.

In China's calendar, A, B, C, D, E, Ji, G, Xin, Man and Ghost are called "ten heavenly stems", while Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai are called "twelve earthly branches". The two cooperate with each other in a fixed order, forming the discipline of cadres and branches.

In Ci Yuan, it is said that "dry branches" are meaningful to trees. Heavenly stems and earthly branches formed a unique calendar in China to record the year, month and day. In the Book of Changes and the system of traditional Chinese medicine, heavenly stems correspond to many related information, such as geographical orientation, images of viscera and other things.