"Some tourists and citizens get used to throwing about plastic bags and disposable bottles on the floor,serving as a chief culprit in environmental protection."(已经不错!)
(1) "throwing about" = throwing away;
(2)"on the floor" 大厦里的地板= on the ground;在路上;
(3) "serving" =this littering 乱抛垃圾;
(4) "a chief culprit" = the main culprit;
(5) "in environmental protection" = in environmental destruction;
建议:"Some tourists and citizens get used to throwing away plastic bags and disposable bottles on the ground.This littering is the main culprit in environmental destruction."