小马和老牛是邻居。一天,主人应朋友的要求,让小马驮两袋种子送去。小马日夜兼程,两天后,完成任务回家。“小马,你真棒!爹妈给了你一副快蹄子。”老牛夸赞小马。“听妈妈说,我们的蹄子是祖先在草原上慢慢进化出的。大约六千万年前,我们的祖先只有约半米高,根本跑不快。后来,它们为应对强敌袭击,不得不努力跑快点。再后来,它们的身体变高大,脚趾和肉垫进化成了蹄子。”小马耐心地给老牛解释。“对了,你为什么总站着睡觉,不累吗?”老 Pony and cow are neighbors. One day, the owner should be friends at the request of the pony pack two bags of seeds to send. Pony day and night, two days later, complete the task to go home. “Pony, you’re awesome!” Father gave you a pair of fast hooves. “Old cow praised the pony. Listening to my mom, our hoofs were slowly evolved by ancestors on the prairie: About 60 million years ago, our ancestors were only about half a meter tall and did not run well at all. Later, in response to strong enemy attacks, Do not try to run faster, and later they grew taller, their toes and pads evolved to hoofs. ”The pony patiently explained to the cow. “Yes, why do you always stand to sleep, not tired?”