问题
选择题
下面的图中，正确表示水沸腾时杯底气泡向上升的图示是（ ）
A．
B．
C．
D．
答案
答案：A
题目分析：水受热沸腾前，水的下方温度较高，上层的水温度较低，气泡上升时，遇到上层温度低的水，液化且气泡变小；沸腾时整个容器中的水温度都相同，气泡上升的过程中，气泡在水中的深度越来越浅，所受的压强越来越小，气泡越来越大至液面破裂．故选A．
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下面的图中，正确表示水沸腾时杯底气泡向上升的图示是（ ）
A．
B．
C．
D．
答案：A
题目分析：水受热沸腾前，水的下方温度较高，上层的水温度较低，气泡上升时，遇到上层温度低的水，液化且气泡变小；沸腾时整个容器中的水温度都相同，气泡上升的过程中，气泡在水中的深度越来越浅，所受的压强越来越小，气泡越来越大至液面破裂．故选A．
| 根据短文内容，在后面的方框中选择正确的答案填入短文中，使短文内容完整。 | |
| Hello, my name is Lin Tao. 1 . There are nineteen boys and twenty-eight girls in my class. 2 His name is Sam Smith. He’s thirteen. He is tall and strong. 3 They are twin sisters. Their names are Kate and Joan. They are thirteen. Their mother Mrs. Miller is an English teacher of our school. They are my friends. They like playing badminton. 4 They like Beijing Opera very much, but they can only speak a little Chinese. 5 Our Chinese students all like the English boy and the American girls, and they like us, too. . | |
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