资料题：Being able to swim has always been a (an)（　）。

Being able to swim has always been a valued skill.But competitive swimming is just over one hundred years old.Racing in the water began in Europe only about fifty years before the first modem Olympics.England was the leader in this new sport.Pools were built and races were held.Interest was aroused when a group of Native Americans went to England in 1844 to swim against an English team.To the surprise and dismay of the English, the Americans beat them easily.At that time the English used the breast stroke, which was thought a good form.The Americans used a kind of free style that was much faster.A short time later an English family, who had moved to Australia, developed the crawl, an overhand swimming method, which was later spread to America.Charles Daniels, an early userof the crawl, changed the kicking rhythm to develop the American crawl.