What's the date of April 20th next year?

The lunar calendar is the current modern calendar in China. It belongs to the combined calendar of yin and yang, that is, the combined calendar of lunar calendar and solar calendar. According to the change cycle of the moon phase, each moon phase changes to one month, and the leap month is set with reference to the length of a year in the tropical year of the sun and 24 solar terms, so that the average calendar year can adapt to the tropical year. The lunar calendar combines the lunar calendar with the solar calendar to form the yin-yang calendar. Because of the use of "Xia Zheng", it was called Li Xia in ancient times.

Lunar calendar is a new calendar used after 1970. Its years are divided into normal years and leap years. The normal year is 12 months, and the leap year is 13 months. Month is divided into big month and small month. There are 30 days in the big moon and 29 days in the small moon. The average calendar month equals the new moon.