用英语介绍重阳节：Double Ninth Festival is a traditional Chinese Folk Festival, which is held on the ninth day of the ninth lunar month every year.
The number of "Nine" is Yang in the book of changes. The two Yang numbers of "Nine" are equal, so it is called "double Yang"; Because both the sun and the moon meet nine, it is also called "double nine".

重阳节，是中国民间传统节日，节期在每年农历九月初九日。“九”数在《易经》中为阳数，“九九”两阳数相重，故曰“重阳”；因日与月皆逢九，故又称为“重九”。