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出语言错误。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，并在该词下写出修改后的词

注意：1.没处错误及其修改均限一词；

2.只允许修改10处，多者（从第11处起）不计分。

May 10,2009                                              Fine

Today I was having a PE lesson while I fell down and hurt my foot. I was in greatly pain at that moment,     but I tried to act as if nothing has happened until the class was over. Though I had difficulty walk back to my classroom, I still didn’t tell anyone but even refused the offer of help of my classmates. As result, the hurt in my foot become worse. Now I know I was wrong. We can tell others our need for help and accept his help. Some day we can not help others in return. In this way, we can get along to each other happily and peacefully.

地基处理方法中，既可用于加固深1～4m厚的软弱土、湿陷性黄土、杂填土等地基，还可用作结构辅助防渗层的是（）。

A.灰土地基

B.砂和砂石地基

C.粉煤灰地基

D.矿渣地基