问题
问答题 简答题
绘图题：画出汽包锅炉的自然循环过程。
答案
参考答案：
水自汽包进入下降管，通过下部联箱进入水冷壁吸热而蒸发，汽水混合物进入汽包，分离后，蒸汽去过热器加热。工质沿特定回路的循环称自然循环。如图所示：
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绘图题：画出汽包锅炉的自然循环过程。
参考答案：
水自汽包进入下降管，通过下部联箱进入水冷壁吸热而蒸发，汽水混合物进入汽包，分离后，蒸汽去过热器加热。工质沿特定回路的循环称自然循环。如图所示：
| 阅读下面短文，掌握其大意。然后从A、B、C、D四个选项中选出最佳选项。 | ||||
| Many scientists say that the world is getting hotter and hotter. If they are right, the ice at the North and South Pole will melt eventually. If this happens, the sea will rise and may cover most 1 all of Singapore. This will force everybody to move to a 2 country. We know that the sun 3 the earth. The heat from the sun hits the 4 , and some of it goes back into the sky. However, factories and cars 5 a lot of carbon dioxide (二氧化碳). When the gas rises into the sky, the heat from the sun can come 6 them but the heat from the ground cannot. It 7 near us in the sky and makes the 8 hotter and hotter every year. Scientists call this the "greenhouse effect" because a greenhouse is a small glass 9 which is hot inside. It is used for growing plants in cool countries. Many countries are 10 about the greenhouse effect. They are trying to stop factories and cars from sending 11 gases into the sky. Scientists are not sure when the world will get much hotter. Some people say that the greenhouse effect has 12 already and has begun to affect the world's weather. | ||||
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