December 21 is the 355th day of the year (356th in leap years) in the Gregorian calendar; 10 days remain until the end of the year.

2009年12月9日 · 12、13也一样所以11~20都是 ……th从21开始就有规律了。21为twenty-first 所以是 21st. 总结：即个位是1就是st，个位是2就是nd，个位是3就是rd，其他个位就是th（务必记住20以后才适用，11，12，12是例外，都用th） 参考资料来源：百度翻译-12月11日、12月12日 …

2012年12月20日 · Historical events for the 21st of December. See what famous, interesting and notable events happened throughout history on December 21.

On This Day In History - December 21: anniversaries, birthdays, major events, and time capsules. This day's facts in the arts, politics, and sciences.

“21st” is the correct form to indicate the ordinal number between 20th and 22nd. “21th” is an irregular ordinal number, because it ends with 1. The number one, as an ordinal number, is “First” – and the suffix used to indicate that is “-st”. That’s why we use “1st”, “21st”, “31st”, etc.

2012年12月21日 · What happened on this day in history, December 21. See what historical events occurred, which famous people were born and who died on December 21.

12月21日 英语写作 21st December，读作 the twenty-first of December，这是英式写法，月份放在日期后面。 12月21日 中文读作 十二月二十一日，与美式英语相同，也是月份放在日期前面。

December 21st is known as Look On The Bright Side Day & Phileas Fogg Win A Wager Day. Welcome to day 355 of the year folks, there are just 4 days left until Christmas & 10 days left in 2025. At some point today, we’ll have exactly one million seconds left of 2025.

On December 21, 1891, 30-year-old James Naismith introduces the first game of basketball. Based on 13 rules created by Naismith, the game is tested by 18 students at the International Young Men ...

Discover what happened on December 21 with HISTORY’s summaries of major events, anniversaries, famous births and notable deaths.