Tubes should be laid at 0.5 m to 1.0 m depth in heavy soils and deeper in lightsoils.
排水管在硬质土壤中埋的深度为0.5 - 1.0米，在软质土壤中要埋的更深一些。
2
The sources, definition and soils of the light pollution are analyzed.
指出了光污染产生的原因和光污染的定义及分类。
3
This soil has promising future due to its advantages such as light weight, high strength, self-standing, short project execution time, re-utilization of surplus soils, and environmental friendliness.