英文關鍵字
architecture
beneath
channel
collector
concrete
construction
dark
dirty
drain
drainage
end
exit
flow
flowing
ground
industrial
industry
inside
light
mine
old
passage
pipe
pipeline
pollution
rain
rainwater
sewage
sewer
sewerage
shining
shot
stabilized
stone
storm
stream
sunlight
system
tracking
tube
tunnel
underground
underneath
urban
walls
waste
wastewater
water