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。

    Great changes have been taken place in my village. Ten years ago, the small and low houses of my village lie on the north of a lake. The villagers produced many waste. As a result, the lake was serious polluted. To the west of the village was a sandy field, where was the source of much dust.

    Now the poor house have been replaced by green trees. However, the sandy field that the villagers used to plough has been covered of fruit trees. On the lake, now clean and clear, the villagers often spend their spare time fish.

    In word, my village has become a green one.

答：空气受热体积膨胀，由密度公式可知，质量一定时，体积变大，密度____而上升．热空气上升后，温度低的空气就从四面八方流过来从而形成____使纸风车转动．

一个物体孤立静止放置在某个支承面上时，它对支承面的压力与它受到的重力是否相等？某科学兴趣小组针对这一问题做了如下实验：将重为5牛的木块A放在一块木板上，改变木板与水平面之间的夹角，测量木块对木板的压力，再换用重为10牛的木块B重复上述实验，并将有关测量数据填入下表。

表一

表二

根据短文理解，从A、B、C三个选项中选择最佳答案填空。

    A young father was visiting an old man. They were standing in the old man's garden and  1  children. The young man said, "How strict should parents be  2their children?" The old man pointed to a line3 a big, strong tree and a thin, 4  one. "Please untie the line," he said. The young man 5 so, and the young tree bent(弯曲) over to one side.

    "Now tie it again," said the old man, "but first pull the line tight(紧紧地) so that the young tree is6  again." The young man did as the old man told him. Then the old man said, "It is the same with  7  . You must be strict with them, but sometimes you must untie the 1ine8 how they are getting on. If they are not yet able to stand alone, you must tie the line tight 9 . But when you find that they are ready to stand alone, you can take the10   away."