half height line of drift
half height line of drift
[冶金学英汉词典]
half height line of drift巷道腰线
是什么意思，half height line of drift的解释，half height line of drift的翻译
half height line of drift
[冶金学英汉词典]
half height line of drift是什么意思，half height line of drift的解释，half height line of drift的翻译