機器
asphalt
bristle
broom
brush
city
clean
cleaner
cleanup
day
dirt
dirty
driving
dry
dust
environment
equipment
fitness
green
industrial
industry
land
machinery
motion
nature
neat
objects
part
purity
revolving
road
scene
scrub
service
sidewalk
spray
spring
street
summer
sunlight
sweeping
technology
tractor
traditional
transportation
turning
urban
washing
wheel
working