请将下面这段话翻译成英文：

　　秦朝是中国历史上第一个统一的、多民族的、中央集权的、封建王朝(feudal dynasty)。尽管秦朝只持续了15年，但是它在中国历史上扮演着重要角色，对后续朝代产生了重大影响。为了巩固国家统一，维持秦朝永传万代，秦始皇在政治、经济、军事和文化上进行了很多改革。政治上，他宣布自己就是这个国家的皇帝，手握重权。经济上，他统一了度量衡(weights and measures)和货币。另外，他还统一了文字以及车轮之间的距离。世界奇迹—万里长城也是他命令建造的。

　　参考翻译

　　The Qin Dynasty was the first unitary,multi-national and power-centralized,feudal dynasty in Chinese history.Although lasting only for 15 years,it played an important role in Chinese history and exerted a great influence on the foltowing dynasties.To strengthen the unity of the nation and to perpetuate the Qin Dynasty,Emperor Qin Shi Huang carried out many reforms in politics,economy,military affairs and culture.In politics,he declared himself the emperor of the stale in possession of all major powers.In economy,he standardized weights and measures as well as money.In Addition,he standardized the written characters and the distance between two wheels.The miracle of the world,the Great Wall of China was also built under his order.