an image from the US government EPA "Sunwise" program. I converted it from PDF format, and removed all the "sunwise" logos. the source link is here - http://www.epa.gov/sunwise/doc/guide.pdf
書和筆
book、epa、epa sunwise、externalsource、pen、read、school、write
書、EPA、epa sunwise、外部源、噴、讀、學校、寫
資料來源：openclipart ( https://openclipart.org/ )