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新型桩工机械液压静力压桩机具有非常独特的无公害桩基础施工法，尤其适合在城市内部施工。掌握液压静力压桩机的使用特点，熟悉其安全操作的有关规定，并了解它们常见故障的排除，将对液压静力压桩机械的合理使用、安全操作、提高机械施工效率有着十分重要的意义。请问：

静力压桩机的"液压系统噪声太大"故障原因有（）

A.油内混入空气

B.油压太高

C.油管或其他元件松动

D.溢流阀卸载压力不稳定

E.密封件损坏

答案

参考答案：A, C, D

完形填空

After graduation from college, I started to sell. Soon I discovered that the worried expression I      小题1:   (wear)since childhood meant sure failure. I knew it wasn't going to be easy to change that expression on my face left by so many years of      小题2:   （hard）.It called for a complete change in my view on life. Here is the method I tried.

Each morning during a fifteen­minute bath, I determined to cultivate a big, happy smile. I found out, however, that it couldn't be a    小题3:   (force) smile developed just for the purpose of putting dollars in my pocket. It had to be     小题4:   honest­to­goodness smile from down deep inside， an outward expression of happiness from within!

Let's see      小题5:    starting off with a good fifteen­minute training of the smile muscles helped me during the day.   小题6:   entering an office I would think of many things I had to be thankful for, work up a big smile and then enter. Seldom did it fail      小题7:      (get) the same smile    小题8:   return from the person I met. I also found that it pleased people when I passed them on the street to give them a cheerful smile.

Give every living soul you meet the best smile you have ever smiled in your life,    小题9:   see how much better you feel and look. It's one of the best ways I know to stop worrying, and start living. When I began doing this, I found     小题10:     more welcome everywhere.
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选择题

某密闭容器中充入等物质的量的A和B，一定温度下发生反应A(g)＋xB(g) 2C(g)，达到平衡后，在不同的时间段，分别改变影响反应的一个条件，测得容器中物质的物质的量浓度、反应速率分别随时间的变化如下图所示：

下列说法中正确的是（     ）

A．30～40 min间该反应使用了催化剂

B．反应方程式中的x＝1，正反应为吸热反应

C．30 min时降低温度，40 min时升高温度

D．8 min前A的平均反应速率为0.08 mol·L－1·min－1
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