英文關鍵字
channel
collector
concrete
danger
dark
death
deep
dirty
drainage
draining
ecology
environment
factory
flow
industrial
inside
interior
mine
mystery
passage
pipe
pipeline
poison
pollution
river
round
sewage
sewer
sewerage
stink
subterranean
toxic
tube
tunnel
underground
vaulted
voronezh
waste
wastewater
water