英文關鍵字
below
beneath
black
business
cave
cavern
coal
copper
copy
corridor
dangerous
dark
deep
dig
diminishing
dirt
dirty
employment
end
engineering
entrance
escape
gold
hard
history
industrial
industry
inside
interior
labor
lamp
metal
mine
mineral
mining
nature
old
path
perspective
rock
safety
shaft
solitude
stone
texture
tunnel
tunneling
underground
wall
working