假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处错误，每句中最多有两处。错误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∧，并在其下而写出该加的词。

删除：把多余的词用斜线划掉\。

修改：在错的词下划一横线，并在该词下而写出修改后的词。

注意：1．每处错误及其修改均仅限一词；

2．只允许修改10处，多者（从第11处起）不计分。

Our school held an activity on last Sunday because it was "Earth Day". Hundred of students took part in it. I am one of them. First, the headmaster gave us a speech about how to protect earth—our home. Then we went hiking, this was about 15km. Although the hiking was very tired, none were left behind. It is no doubt that all of us like the activity. In the future, they will try hardly to protect the environment. We hope we will take part in more activity about caring about the globe.