假定英语课堂上老师要求同桌之间交换修改作文，请你修改你同桌写的一篇作文，文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加，删除或修改。

增加：在缺词处加一个漏字符号(∧), 并在其下面写出该加的词。

删除：把多余的词用斜线(\)划掉。

修改：在错的词下一横线，并在该词下面写出修改后的词。

注意：1．每处错误及修改均仅限一词；

2．只允许修改10处，多者(从第11处起)不计分。

    Last Sunday, I take part in the “Earth Protector” activity with my classmates. In the morning, we went to a People's Park at 8:30 by bus. When we got to there，we saw some children draw pictures by the lake. The ground and public walls was very dirty. So we began to pick up the rubbish or clean the public walls. We also planted some tree. All of them worked very hard. We think it's our duty to take good care our environment. If everyone protects the environment, the world will become more and more beautifully.