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。
Dear Editor,
I'm writing to tell you about a shocked incident that happened in Beijing Zoo in the afternoon of Feb 23rd.
I was visiting the zoo that afternoon while I heard bears roaring terribly. I hurried to the place where the bears lived at. I saw the black bear badly injured and one of them roll on the ground painfully. It was hurt too serious to move a foot. The people around was shocked, angry and blaming the wrongdoer. I learned that was a student from a famous university in Beijing who caused the trouble. He pulled sulfur and acid onto the bears or pretending to feed them.
What an shame! Animals are our friends and something must be done to prevent them from being injured.
Sincerely Yours
Li Hua