The draft of coal mine excavation plan is typically an unhealthy structural and complex tech economic problem.

矿井采掘计划的编制是典型的不良结构和复杂的技术经济问题。

youdao

The draft of coal mine excavation plan is typically an unhealthy structural and complex tech economic problem.

矿井采掘计划的编制是典型的不良结构和复杂的技术经济问题。

youdao