短文改错（共10小题；每小题1分，满分10分）
英语课上,老师要求同桌同学相互修改作文。假设以下小作文为你同桌所写，请你对其进行修改。文中共有10处错误,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。
3．必须按答题要求做题，否则不给分。
A tornado is a rotated column of air from a thunderstrom to the ground.  The most violent have winds of more than 400 kilometre per hour. Tornadoes can pick up cars, trains and even houses and put it down in the next street --- or even in the next town. They can take the fur out the back of a cat and the feathers off a chicken. They can destroy houses, and leave the furniture inside exactly what it was.
On average, there are 800 tornadoes in the US each year, cause about 80 deaths and 1500 injuries. The worst tornado of all the time occur in 1925, affecting three US states. By the time it ended, more than 700 people had killed and 2700 had been injured.