The most important severe hazard risk is the ground contact condition which arises in transmission poles, fence posts and railway sleepers.

 
  • 危害木材最嚴重的情況,是在木材與地基接觸的條件下發(fā)生的,為通訊電桿,柵欄柱材和鐵路枕木。
今日熱詞
目錄 附錄 查詞歷史
国内精品美女A∨在线播放xuan