英文關鍵字
cave
cavern
development
dig
geology
grey
heavy
industrial
manufacturing
mine
mineral
multicolor
ore
passage
pattern
potassium
produce
purpose
quarry
resource
rock
salt
stone
structure
technology
tunnel
underground
wall
英文關鍵字
cave
cavern
development
dig
geology
grey
heavy
industrial
manufacturing
mine
mineral
multicolor
ore
passage
pattern
potassium
produce
purpose
quarry
resource
rock
salt
stone
structure
technology
tunnel
underground
wall