April is commonly associated with the season of autumn in parts of the Southern Hemisphere, and spring in parts of the Northern Hemisphere, where it is the seasonal equivalent to October in the Southern Hemisphere and vice versa.
The traditional etymology [词源] of April is from the verb aperire, "to open", in allusion [暗指; 典故] to its being the season when trees and flowers begin to "open".
In China the symbolic ploughing of the earth by the emperor and princes of the blood took place in their third month, which frequently corresponds to April. A prince of the blood is someone with direct hereditary [世袭的] lineage [世系] to a monarch [君主].
The UN Chinese Language Day is officially set up on April 20 on the solar calendar, every year, which in the case of 2021 is right coincident with the traditional solar term "GuYu" in China, known as the Grain Rain day, the 6th of the 24 Chinese Solar Terms based on the Chinese lunisolar [lunar+solar] calendar.
现在我国还在使用的夏历(也叫农历或阴历)是阴阳合历。它和阴历一样，以月亮圆缺一次的时间为一个月，大月30天，小月29天。为了调整四季，它用加闰月的办法使每年的平均天数和阳历接近。阴历每过约二到三年多有一个闰月。春秋战国时代有夏历、殷历和周历，它们最主要的区别是岁首的不同，又称“三正”。周历以通常冬至所在的建子之月（即夏历的十一月）为岁首，殷历以建丑之月（即夏历的十二月），夏历以建寅之月（即后世常说的阴历正月）。
April Fools' Day or April Fool's Day is an annual custom on April 1 consisting of practical jokes [trick] and hoaxes [恶作剧]. Jokesters often expose their actions by shouting "April Fools!" at the recipient. Mass media [大众媒体] can be involved in these pranks [玩笑,恶作剧], which may be revealed as such the following day. The day is not a public holiday in any country except Odessa in Ukraine, where the first of April is an official city holiday. The custom of setting aside a day for playing harmless pranks upon one's neighbour has been relatively common in the world historically.
Some writers suggest that April Fools' originated because in the Middle Ages, New Year's Day was celebrated on March 25 in most European towns, with a holiday that in some areas of France, specifically, ended on April 1, and those who celebrated New Year's Eve on January 1 made fun of those who celebrated on other dates by the invention of April Fools' Day. The use of January 1 as New Year's Day became common in France only in the mid-16th century.
One of the most famous April Fools' Day pranks of all time is the BBC's famous "spaghetti harvest" segment. On April 1, 1957, a news broadcaster told his British audience that Ticino, a Swiss region near the Italian border, had had "an exceptionally heavy spaghetti crop" that year.