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

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。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。

Yesterday, I have to post a letter. There weren’t any stamps in the house, but I had to go to the post office. But when I got there, I found I have forgotten to take my wallet. When I was about to leave the post office, I stopped by an old man in front of me. He gave me one of his stamp. Never having been given a stamp for free before, I asked him how many he wanted for it. But surprisingly, she said it was given to me for free. I sincerely thanked for him and went on my way. It was so a small act of kindness. But it was good to knowing that people were still out there being kind to strangers.

1. have—had      2. but –so    3. have—had    4. stopped—was stopped 

5. stamp—stamps   6. many—much       7. she –he

8. for去掉        9. so—such           10.knowing--know