This is the 6211th most frequent Chinese word.
开封
"Kaifeng" – A city in Henan province, China.
In this sentence, '开封' refers to the geographical location Kaifeng, the city.
宋代的开封是当时的文化和经济中心。
Kaifeng during the Song dynasty was a cultural and economic hub.
Here, '开封' describes the state of an envelope that has been opened.
我学习了如何修补开封的信封。
I learned how to repair an envelope that has been opened.
This sentence uses '开封' again as the name of the city, highlighting its historical significance.