煤中微量元素一直是煤田地质学和煤质研究的重要组成部分。

The investigation to trace elements in coal has been of importance to coal geology and coal property for decades.

youdao

煤中微量元素一直是煤田地质学和煤质研究的重要组成部分。

The investigation to trace elements in coal has been of importance to coal geology and coal property for decades.

youdao