他研究了摆线 、 圆外旋轮线和四点圆的旋轮线的几何性质.He investigates geometrical properties of cycloids , epicycloids, and hypocycloids.由于这个缘故,摆线又叫做等时曲线.For this reason the cycloid is called the tautochrone.分析摆线钢球行星传动减速器的振动特性.The vibration perfo...
The missile buried itself deep in the grassy hillside...导弹深深地埋在杂草丛生的山坡上。...grassy, alpine meadows.高山上长满青草的草地Its buildings are half-hidden behind grassy banks.它的建筑群半掩在长满青草的河岸后面。a small tree on a grassy mound翠的山岗上的一棵小树Dirt...