10．Throughout the 1900s，almost everyone knew how to jump，or"skip"rope．And it wasn't just kids on playgrounds chanting silly rhymes or singing favourite songs．Champion boxes like Sugar Ray Leonard and Muhammad Ali jumped rope to build stamina （耐力）and develop quick footwork． The activity of rope-jumping for f（81）un and exercise has most likely been around for thousands of years．Historians believe children skipping rope，and medieval （中世纪的）European paintings s（82）how children skipping rope on the cobblestone （鹅卵石）streets． The earliest jump ropers in North America may have been Dutch immigrants，who brought the game Double Dutch with them in the 1600s．In Double Dutch，two turners h（83）old the ends of two ropes and turn them in opposite directions as one person jumps between them．When the game was first introduced，girls couldn't participate，partly because they were c（84）onsidered weaker，and exercise was thought of as unfeminine （不适合女性的）Also，girls wore l（85）ongdresses that got in the way． Once girls did start jumping，however，they really took over．And later，it was m（86）ainly girls who were better at this activity．Now，both girls and boys jump rope．Jumping rope has become a worldwide competitive sport in which children and adults compete in both single and t（87）eam events． So，pick up a rope，find a silly rhyme or your favorite song，and start jumping．
