短文改错（共10小题；每小题1分，满分10分）
假定英语课上老师要求同桌之间修改作文，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：在错的词下画一横线，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。
The water we drink and use was running short. We all have to learn what to stop wasting water. One of the step that we should take is to find ways of reusing it. Today in the most large cities, fresh water is used only once and then it runs in waste system. But that is possible to pipe the used water to a purifying factory, there the used water can be treated with chemical materials by the workers so that it can reused. But even if every large city purified and reused it’s water, we still would have enough water.