问题
单项选择题
在正常工作条件下，作用水头H、直径d相等时，小孔口收缩断面的流速v和圆柱形外管嘴出流的流速vn（）。
A．v＞vn
B．v=vn
C．v＜vn
D．不定
答案
参考答案：A
解析：
孔口流速系数为0.97，管嘴流速系数为0.82。
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在正常工作条件下，作用水头H、直径d相等时，小孔口收缩断面的流速v和圆柱形外管嘴出流的流速vn（）。
A．v＞vn
B．v=vn
C．v＜vn
D．不定
参考答案：A
解析：
孔口流速系数为0.97，管嘴流速系数为0.82。
| 完形填空。 A terrible earthquake happened in Wenchuan on May 12, 2008. 1 people lost their lives and homes. During those days, a lot of stories about 2 could be heard. Here is one of them. After the earthquake, 3 a fallen building, some soldiers found that a 4 died in a very strange way. When they were ready to take her away, they were surprised to find that a baby in her arms was 5 alive. The baby was sleeping and 6 hurt at all. Between the dead mother _ 7 the living baby, there was a mobile phone with a short 8 on the screen, "My dear baby, if you can survive , remember that I love you." Everyboy 9 when they read these words. Besides this story, many other stories also moved us deeply. 10 these stories, we know more about love. You're lucky if you're loved by others. You're great if you love others when you're in danger. | ||||
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