问题
填空题
发电机启动必须保持空负荷，待低转速运转（）分钟后，逐渐加速，升压至正常位置.
答案
参考答案：3－5
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发电机启动必须保持空负荷，待低转速运转（）分钟后，逐渐加速，升压至正常位置.
参考答案：3－5
| 阅读理解。 |
| In some parts of the United States, farming is easy. But farming has always been difficult in the northeastern corner of the country, which is called New England. New England has many trees and thin, rocky soil. Anyone who has wanted to start a new farm there has had to work very hard. The first job has been cutting down trees. The next job has been digging the stumps of the trees out of the soil. Then the farmer has had the difficult job of removing stones from his land. This work of removing stones never really ends, because every winter more stones appear. They come up through the thin soil from the rocks below. Farmers have to keep removing stones from the fields. Even today, farms which have been worked on for 200 years keep producing more stones. That is why stone walls are used instead of fences around New England fields. The stone walls are not high; a man can easily climb over them. But they keep the farmer's cows from joining his neighbor's cows. |
| 1. This selection explains _____. |
| A. how to make a stone wall in New England B. why there are many stone walls in New England C. which parts of New England first used stone walls D. how many fences there are in England |
| 2. According to this selection farming is difficult in New England because _____. |
A. the winter is very long there |
| 3. This selection says that the work of removing stones _____. |
| A. must be done again and again B. is usually done during the winter C. was more difficult before machines were used D. is easy after machines were used |
| 4. In New England, stone walls are used _____. |
| A. to protect the farmer's fields from thieves B. to keep the farmer's cattle from wandering away C. to provide privacy for the farmer's family D. to prevent the wind from blowing away the earth |