1) coal resources "three unders"
三下压煤
2) mining of seams in conditions of"three unders-one above"
"三下一上"压煤开采
3) the coal-hunting theory beneath three strata
"三下"找煤
4) "three unders" mining
"三下"采煤
1.
Yungang Mine is typical “three unders” mining district in which there is a big area together with water, railway and buildings.
云冈矿“三下”压煤面积大,且建筑物、水体、铁路连成一体,为典型的“三下”采煤。
5) sanxia caimei
三下采煤
6) coal block under urban area
城市下压煤
补充资料：压一
1.压倒或超过一切;第一。
说明：补充资料仅用于学习参考，请勿用于其它任何用途。
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