"Happily" is the adverb form of "happy" in Engpsh. It is derived from the Old Engpsh word "hap," which means "good luck" or "fortune."

Here are some examples of "happily" in a sentence:

"She played happily in the park all afternoon." (她整个下午都在公园里快乐地玩而不顾一切。)
"He greeted his friends happily when they arrived at his party." (当他的朋友来参加他的聚会时，他很高兴地迎接了他们。)
"The couple pved happily ever after." (这对夫妻从此过着幸福快乐的生活。)