What do a, b, c and d mean?

A, B, C and D are basic words in Chinese, which represent four different heavenly stems and are used to mark the order and classification of days.

A is the first day of ten days' work, which stands for the meaning of beginning, source, leadership and first place. B is the second day of ten days, representing growth, development, coordination and cooperation. C is the third day of ten-day work, representing the meaning of accommodation, transmission, connection and transformation. Ding is the fourth day of ten days, representing light, hope, progress and progress.

A, B, C and D Tiangan were widely used in ancient China. They are not only used to mark dates and times, but also used in naming, divination, geomantic omen and other fields. In modern Chinese, ethylene, propylene and butyl are also widely used. For example, in the medical field, these four heavenly stems are used for the names of hepatitis A, hepatitis B, hepatitis C and hepatitis D. In addition, methyl ethyl propyl butyl is also used to name some chemical elements and compounds.

The Application of Four-day Dried Ethylene-propylene-Butyl in Ancient China;

In the theory of five elements, A and B belong to wood and C to fire, which are used to express five different properties and strengths. The nature of wood is considered to be growth, development and prosperity, while fire represents light, heat, energy and change.

In ancient divination, A, B and D also played an important role. They are used to express different divinatory symbols and meanings, and are an important basis for interpreting divinatory symbols and the Book of Changes.

A, B, C and D are also used to name some important historical events and people. For example, during the Yongle period of the Ming Dynasty, Emperor Judy sent Zheng He to the Western Ocean seven times, and later generations called this historical event "the occasion of Party A and Party B" to commemorate this important historical moment.

In ancient astronomy, A, B and D were also used to mark different constellations and galaxies. For example, the first star in the Big Dipper is called "One Star", while the first star in the six stars in Nandou is called "Ding Xing".

In ancient China, A, B, D and C had very wide application value and cultural significance. They are not only an important part of language and culture, but also have a far-reaching impact on China's history, culture, philosophy and science.