In the lunar calendar, June 1 1 in some years is a big month with 30 days, and June 1 1 in some years may be a small month with 29 days.
Lunar calendar is the current modern calendar in China, which 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 reference solar year is the length of one year, 24 solar terms are added, and leap months are set to make the average calendar year adapt to the tropic year.