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。

    To show our love for poor kids lived in earthquake-hit areas, our school hold a special activity recently in our school lecture hall. Its purpose was to making sure those poor kids have a warm winter. All the teachers and students in our school took an actively part in this activity. We gave away 400 pieces of clothes and 200 pairs of shoe altogether. After be sorted, they will be sent to those in the need. I believe what they did will make a great difference to those poor kids. Although we all learn to care for others, the world will be more comfortable to live.

水土流失是形成黄土高原千沟万壑自然景观的主要原因，每年流失的土壤约16亿吨，黄土高原水土流失严重，最主要人为原因是(     )