Heaths normally develop on poor sandy well-drained soils in temperate climates and are usually subclimax communities maintained by grazing burning and sometimes cutting.
正常情况下石楠灌丛生长在温带的贫瘠,含沙的或是排水良好的土壤上,放牧,焚烧和不时地砍伐通常使石楠灌丛亚顶极群落得以维持。
The pressure of slotted pipes in a sandy well was analyzed. The bottom hole pressure was computed. A model for computing the bending strength and stiffness of a slotted pipe was proposed.
对割缝衬管在防砂井中受外挤力作用进行了分析,计算了井底压力(包括流体流经砾石层和割缝衬管的压降) ,建立了衬管割缝参数与割缝条幅弯曲强度及刚度之间的关系式。
Some savannas occur on wet, waterlogged soils; others on dry, sandy, well-drained soils.
一些稀树大草原生长在潮湿、涝渍的土壤上;其它则在干燥、多沙、排水良好的土壤上。
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