Not quite right. Singularity is a common name for positive numbers and odd numbers in mathematics, and positive integers that are not divisible by 2 are called singular numbers. In the Gregorian calendar, the date of February 29th added to make up for the time difference is called leap day, and the years divisible by 4 or 400 are leap years, with a leap of four years, a leap of one hundred years and a leap of four hundred years. Odd years are not even divisible by 2, let alone 4 and 400. Therefore, odd years are indeed average years according to the Gregorian calendar; Not necessarily if it's a lunar calendar. In the lunar calendar, the month added to make up for the time difference is called leap month, and even solar terms in the 24 solar terms are neutral. In the lunar calendar, a leap month is added to a non-neutral year, which is designated as a leap year, a leap every three years, a leap every five years and a leap every nineteen years. So odd years are not necessarily the average years according to the lunar calendar.