Groundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions.
地下水通常聚集在河流流域，但在干旱地区，地下水也可能完全保留在干涸河床的表面之下。
2
Following the Mama Bongisa advice, they mounded the earth to get as much surface area as possible and to prevent Kinshasa's harsh rains from flooding the beds.
按妈妈促进会的建议，他们堆起土，尽可能地扩大面积并防止金沙萨的暴雨冲垮菜地。
3
A major advantage of fluidised beds is that they provide a well mixed, high surface area, fluid-solid system which is useful for efficient reactions and heat transfer.