英文關鍵字
america
beneath
black
cave
coal
copper
copy
corridor
damp
dangerous
dark
deep
dig
diminishing
dirty
employment
engineering
entrance
gold
hard
history
horror
industrial
industry
inside
job
labor
lamp
lighting
mine
mineral
mining
mystery
nobody
obsolete
old
path
perspective
rock
safety
shaft
skill
stone
texture
tunnel
tunneling
underground
usa
wall
working