精选优质文档-倾情为你奉上概要写作参考范文People hold mixed opinions towards dirt on our skin.（要点1: 5分）In the 16th century, people of some European countries, believed that dirt protected people from getting ill.（要点2: 6分）However, People began to change their attitudes to dirt more than 200 years ago. They have been told that washing dirt off our body can keep us healthy. (要点3：8分) Nevertheless, nowadays, some scientists believe that exposure to some dirt may help our immune system. (要点4: 6分)People hold mi
