Suetion devices are inadequate in gravels or very porous soils.吸水装置对砂砾或非常疏松的土壤是不适用的.They may form concentrated pockets in gravels.它们可能在砾石堆积物中形成富集的矿囊.Graves are a mix of gravels, clay and sand carried out by the river.它混合...

gravels的音标：...

n.沙砾( gravel的名词复数 )，砾石，石子，结石...