利用する
abstract
arrow
background
banner
blackboard
blank
blankness
board
business
chalk
chalkboard
circle
circulation
classroom
clean
concept
course
cycle
cyclic
cycling
design
disposal
dispose
eco
ecological
education
elements
environment
environmental
environmentally
flat
frame
fresh
friendly
garbage
glass
grunge
healthy
icon
industrial
industry
isolated
label
lacunae
loop
natural
nature
pattern
pictogram
plank
pollution
problem
recurrence
recycling
refuse
relation
reuse
rubbish
safe
school
schoolroom
scrap
solution
symbol
tag
teaching
texture
utilization
waste
write