英文關鍵字
accident
asphalt
background
breakthrough
cartoon
circle
circular
city
construction
cover
culvert
detail
dirty
ditch
drain
drainage
drop
environmental
flow
gray
hatch
heavy
hole
industrial
industry
iron
manhole
metal
old
pipe
plumbing
pollution
road
round
rusty
sewage
sewer
sewerage
sidewalk
steel
street
surface
texture
tube
underground
urban
waste
water
white