问题
单项选择题
为减少污垢热阻，应（）。
A.降低流体流速
B.采用粗糙度大的管壁
C.采用导热系数大的管壁
D.定期清洗换热器
答案
参考答案：D
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为减少污垢热阻，应（）。
A.降低流体流速
B.采用粗糙度大的管壁
C.采用导热系数大的管壁
D.定期清洗换热器
参考答案：D
| 阅读理解。 |
| In England, people don't usually talk very much. You can go on a bus, or in a train, and everyone (每个人) sits looking out of the window. Often they read. They read books and papers. But they don't talk much. When you meet English people, they often talk about one thing-the weather. So when you meet someone in England, you can say,"Nice weather for the time of year!" "But it was a little cold yesterday." Someone may answer. "But it was warm later." You can answer. If you talk like this, the English will think,"How friendly (友好的) you are!" |
| 1. ______ people don't talk much in a train. |
[ ] |
| A. Chinese B. Canadian C. English D. American |
| 2. English people often ______ on a bus. |
[ ] |
| A. sit talking B. sit sleeping C. sit looking at you D. sit looking out of the window |
| 3. English people often talk about the ______ when they meet. |
[ ] |
| A. children B. weather C. books D. sports |
| 4. English people often read ______ on a bus or in a train. |
[ ] |
| A. books B. papers C. cartoon D. books and papers |
| 5. The English ______ when you talk about the weather with them. |
[ ] |
| A. will think you are friendly. B. will think you like the weather. C. will not think you are friendly. D. will not think you like the weather. |