短文改错。
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：在缺词处加一个漏词符号，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的词。
注意: 1. 每处错误及修改均仅限一词；
2. 只允许修改10处，多者（从第11处起）不计分。
Great changes have been taken place in my village. Ten years ago, the small and low houses, which
lie on the north of a lake, produced much waste. As the result, the lake was serious polluted. To the
west was a sandy field, that was the source of dust. Better still, a brickyard on the southwest side of
the lake used up a great deal good soil. Now the poor house have been replaced by green trees and the
brickyard by tall buildings. The sandy field that the villagers used to ploughing has been covered with fruit
trees. On the lake the villagers often spend his spare time boating and fishing.
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断根拔除术，术中断根突然消失，此时首先应做的是（）。