這段英文變中文！！

The Great Wall was originally built in the Spring, Autumn, and Warring States Periods as a defensive fortification by the three states: Yan, Zhao and Qin. The Great Wall went through constant extensions and repairs in later dynasties. In fact, it began as independent walls for different states when it was first built, and did not become the "Great" wall until the Qin Dynasty. Emperor Qin Shihuang succeeded in his effort to have the walls joined together to fend off the invasions from the Huns in the north after the unification of China. Since then, the Great Wall has served as a monument of the Chinese nation throughout history. A visit to the Great Wall is like a tour through the history backwards; it brings tourists great excitement in each step of the wall.