英文關鍵字
attention
building
canalization
cast
city
construction
cover
danger
day
deep
dig
dirty
district
fence
grid
ground
hard
harsh
hydrogen
industrial
industry
iron
job
methane
moscow
outdoor
pan
pipe
pit
repair
residential
sanitary
sewage
sewer
sign
street
sulphide
summer
town
trees
tube
underground
unsecured
urban
utilities
warning
work
working
yellow