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短文。短文中共有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（∧），并在此符号下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

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。

    Last year,I went shopping in a department store.Little do I know that I was heading for a very new experience. While I was walking around the store,I happened to see the foreigner trying to explain herself with a salesman. Gathering her courage,I decided to step in and helped her explain herself.Fortunately,I could understand that she was talking about,so I just translated it into Chinese.

    I felt glad for able to help her and talk with her.She said that she was a student like me and was touring China lonely.She told me about some experience she had touring the country.Although I won't see her again,but it's good to meet someone like her from another country.

如图，P为⊙O外一点，PA、PB分别切⊙O于点A、B，CD切⊙O于点E且分别交PA、PB于点C，D，若PA=4，则△PCD的周长为（　　）

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经过测算，地球的平均半径为（    ）

下列不属于排泄的是（　　）