来自front,前面的,原义为前线部队,边疆。后用于美国西部大开发时期拓荒者,边远居民。
What is the frontier? ... In the census reports it is treated as the margin of that settlement which has a density of two or more to the square mile. [F.J. Turner, "The Frontier in American History," 1920]
来自柯林斯例句
来自柯林斯例句
来自《权威词典》
来自《简明英汉词典》
来自《简明英汉词典》