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问题 单项选择题

关于高速水流反冲洗，下列叙述有误的一项是（）。

A、利用流速较大的反向水流冲洗滤料层，使整个滤层达到流态化状态，且具有一定的膨胀度

B、截留于滤层中的污物，在水流剪力和滤料颗粒碰撞摩擦双重作用下，从滤料表面脱落下来，然后被冲洗水带出滤池

C、冲洗效果取决于冲洗强度，冲洗强度过小，滤层孔隙中水流剪力小；冲洗强度过大，滤层膨胀度过大，滤层孔隙中水流剪力也会降低，且由于滤料颗粒过于离散，碰撞摩擦几率也减小

D、冲洗流速过大或过小，冲洗效果均会下降

答案

参考答案：C

单项选择题

提高工作绩效、控制企业成本、吸引保留优秀员工、塑造良好企业文化，能发挥上述作用的管理活动是（）

A.监控管理

B.考勤管理

C.薪酬管理

D.督导管理
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单项选择题

Recently, I flew to Las Vegas to attend a meeting. As we were about to arrive, the pilot announced with apology that there would be a slight (16) before setting down. High desert winds had (17) the airport to close all but one runway. He said that we would be (18) the city for a few minutes waiting to (19) . We were also told to remain in our seats meanwhile with our seat belts fastened (20) there might be a few bumps(颠簸). Well, that few minutes turned into about four-five minutes, including a ride that would make a roller coaster(过山车) (21) by comparison. The movement was so fierce that several passengers felt (22) and had to use airsickness bags. As you might guess, that’ s not a good thing to have happen in a(n) (23) space because it only (24) to increase the discomfort of the situation.

About twenty minutes into the adventure, the entire airplane became very (25) There was now a sense of anxiety and fear that could be (26) noticed. Every passenger simply held on for dear life …except one. A (27) was having a good time！ With each bump of the (28) , he would let out a giggle (咯咯地笑)of delight. As I observed this, I (29) that he didn’t know he was supposed to be afraid and worried about his (30) . He neither thought about the past nor about the future. Those are what we gown--ups have learned from (31) . He was (32) the ride because he had not yet been taught to fear it. Having understood this, I took a deep breath and (33) back into my seat, pretending I was (34) on a roller coaster. I smiled for the rest of the flight. I even (35) to giggle once or twice, much to the chagrin(随恼) of the man sitting next to me holding the airsickness bag.

（30）（）

A．health

B．safety

C．joy

D．future
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