Enlisted personnel are identified by way of their various 'E' grades ranging from E-1 to E-9. For those service branches recognizing a Warrant Officer rank, 'W' grades range from W-1 to W-5. Likewise Officers are scaled from O-1 to O-10.
China has quite a collection of natural bridges, including one that experts say has the longest span of any natural bridge in the world. The Fairy Bridge (Xianren Qiao), in southwestern China's Guangxi Zhuang Autonomous Region near the border with Vietnam, has a 400-foot span.
By contrast, the Dictionary of Geological Terms defines a natural bridge as a natural arch that spans a valley of erosion.. The largest natural arch, by a significant margin, is the Xianren Bridge in China, with a span of 122 Â± 5 meters (400 Â± 15 ft). 1  1 Coastline.