有一流量为45000m3/d的机械搅拌絮凝池，共分3格，每格容积174m3，在15℃时计算出各格速度梯度为G1=75s-1、G2=50s-1、G3=25s-1，如果将该池改为三段流速的水力搅拌絮凝池，各格速度梯度不变，不计水力隔板所占体积，则第一格水力搅拌絮凝池前后水面高差计算值是（）m（水的动力黏度μ=1.14×10-3Pa·s，水的体积重量=9800N/m3）。
A．0.22
B．0.12
C．0.32
D．0.04
参考答案：A
解析：
絮凝池每格的停留时间
则第1格得：
得
即第1格水力搅拌絮凝池的水头损失为0.22m，也即第1格的前后水面高差为0.22m。
| Read Mary's questions and choose Tom's answers. Write the correct letters in the boxes. 根据问题，选择正确答案。 |
| 1. Mary: Who is Steven? Tom: |
[ ] |
| A. Steven is very strong. B. Steven works in a department store. C. Steven is my good friend. |
| 2. Mary: How often do you take a shower? Tom: |
[ ] |
| A. I like to play ping-pong. B. Three times a week. C. Basketball is hard. |
| 3. Mary: Would you like to have a cup of coffee? Tom: |
[ ] |
| A. I like coffee. B. Coffee and tea are different. C. Yes, please. |
| 4. Mary: Is playing soccer your favourite sport? Tom: |
[ ] |
| A.Yes, it isn't. B. Yes, I like it best. C. No, it is. |
| 5. Mary: Did you have fun today? Tom: |
[ ] |
| A.Yes, we don't. B. Yes, we did. C. Yes, we do. |