一些图片：
http://www.limerickcorp.ie/services/environment/photos/litter_in_bins.jpg
http://phoenix.gov/STREETS/eglobe.gif
http://img.dell.com/images/global/corporate/environment/windmills.jpg
http://www.easystreetinc.com/images/recycle.jpg
http://www.tumble.com/demo_area/s-p/gifs/corp3.wld.gif
http://www.supergreetingcards.com/cards/2207.jpg
关于环境保护的讽刺漫画：http://www.peterkuper.com/environment/environment.htm
