nián/yue/rì，年/月/日，year/month/day。
qián nián，前年，the year before last year。
qù nián，去年，last year。
jīn nián，今年，this year。
míng nián，明年，next year。
hòu nián，后年，the year after next year。
shàng gè yuè，上个月，last month。
zhè gè yuè，这个月，this month。
xià gè yuè，下个月，next month。
qián tiān，前天，the day before yesterday。
zuó tiān，昨天，yesterday。
jīn tiān，今天，today。
míng tiān，明天，tomorrow。
hòu tiān，后天，the day after tomorrow。
年月日，是一种指计时单位，人们根据地球自转，产生昼夜交替的现象形成了“日”的概念；根据月亮绕地球公转，产生朔望，形成“月”的概念，根据地球绕太阳公转产生的四季交替现象而形成了“年”的概念。
Year, month, and day are a unit of time. People form the concept of “day” according to the rotation of the earth and the phenomenon of alternating day and night; according to the moon’s revolution around the earth, it produces synodic and forms the concept of “moon”, according to the earth’s revolution around the sun The resulting alternation of the four seasons has formed the concept of “year”.
概念由来
年月日，这三个概念所依据的物质运动是互相独立的。根据精确测定，地球绕太阳公转一周的时间约为365.2422平太阳日，这叫一个回归年。而从一次新月到接连发生的下一次新月的时间间隔为29.5306平太阳日，这叫一个朔望月。
Origin of the concept
Year, month and day, the material movements on which these three concepts are based are independent of each other. According to accurate measurements, the time for the earth to revolve around the sun is about 365.2422 mean solar days, which is called a tropical year. The time interval from one new moon to the next new moon in succession is 29.5306 average solar days, which is called a synodic moon.
计算方法
历法是推算年、月、日的长度和它们之间的关系，制订时间顺序的法则叫”历法”。以回归年为单位，在一年中安排多少个整数月，在一个月中又安排多少个整数天的方法和怎样选取一年的起算点的方法就叫历法。
历法问题的复杂性全在于回归年和朔望月这两个周期太零碎，它们同”日”之间的关系，不像公里同米之间的关系那样简单；而且，它们彼此之间也不能通约。所以，历法总是顾此失彼，不能同时协调两个周期。由于这两个原因，历法一般地分为三类；太阴历、太阳历和阴阳历。侧重协调朔望和历月关系的叫太阳历，简称阳历；兼顾朔望月和回归年、历月和历年的叫阴阳历。
无论哪一种历法，都有一个协调历日周期和天文周期的关系间题。在原则上，历月应力求等于朔望月，历年应力求等于回归年。但由于朔望月和回归年都不是整日数，所以，历月须有大月和小月之分，历年须有平年和闰年之别。通过大月和小月，平年和闰年的适当搭配和安排，使其平均历月等于朔望月，或平均历年等于回归年。这就是历法的主要内容。
计算工具
“历书”是排列年、月、节气等供人们查考的工具书。历书在我国古时称通书或时宪书，在封建王朝的时代，由于它是皇帝颁发的，所以又称”皇历”。
Calculation method
The calendar is to calculate the length of the year, month, and day and the relationship between them. The rule of time sequence is called “calendar”. Taking the tropical year as the unit, how many whole-number months are arranged in a year, how many whole-number days are arranged in a month, and how to choose the starting point of the year are called calendars.
The complexity of the calendar problem lies in the fact that the two cycles of the tropical year and the synodic month are too fragmented. The relationship between them and the “day” is not as simple as the relationship between kilometers and meters; moreover, they cannot be negotiated with each other. . Therefore, the calendar always considers one and the other and cannot coordinate two cycles at the same time. Due to these two reasons, calendars are generally divided into three categories; Lunar Calendar, Solar Calendar, and Lunar Calendar. The solar calendar that focuses on coordinating the relationship between the synodic and the calendar month is called the solar calendar; the solar calendar that takes into account the synodic month and the return year, the calendar month and the calendar year is called the lunar calendar.
No matter what kind of calendar, there is a problem of coordinating the relationship between the calendar day cycle and the astronomical cycle. In principle, the calendar month should be equal to the synodic month, and the calendar year should be equal to the return year. However, since the synodic month and the tropical year are not the number of whole days, the calendar month must be divided into a large month and a small month, and the calendar year must be different from a normal year and a leap year. Through the proper collocation and arrangement of large and small moons, normal years and leap years, the average calendar month is equal to the synodic month, or the average calendar year is equal to the tropical year. This is the main content of the calendar.
Calculation tool
“Almanac” is a reference book for people to check the year, month and solar terms. The almanac was called Tongshu or Shixianshu in ancient my country. In the era of feudal dynasties, it was also called “imperial calendar” because it was issued by the emperor.
