high-grade highways

• 高等级公路

high-grade highways的用法和样例：

例句

1. The highway running through the Taklimakan Desert is a long-distance graded highway,the first one in the world built on shifting sands.
   穿越塔克拉玛干大沙漠的沙漠公路，是世界上首次在流动性大沙漠上修筑的长距离等级公路。