coal industry upgrading

英 美
  • 煤炭工业产业升级
  • coal n.煤;木炭vt.烧成炭;供应煤vi.加煤;装煤
  • industry n.工业;产业;行业;勤勉;勤劳
  • upgrading n.提升;浓缩动词upgrade的现在分词.