由于这种采煤方法在实际当中很少应用，目前还缺乏这方面的系统理论研究。

For this mine method is few applied in fact, and lack theory study in this method at present.

youdao

由于这种采煤方法在实际当中很少应用，目前还缺乏这方面的系统理论研究。

For this mine method is few applied in fact, and lack theory study in this method at present.

youdao