機器
asphalt
brush
brushes
city
clean
cleaner
cleaning
cleanliness
cleanup
closeup
conceptual
day
dirty
dust
ecology
equipment
garbage
industrial
industry
iron
land
machinery
mechanca
mechanization
metal
modernization
motion
movement
municipal
outdoors
progress
purity
road
rubbish
scrub
service
side
sidewalk
street
street sweeper
sweeper
sweeping
technology
urban
vehicle
view
waste
wheel
work