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问题 多项选择题

下列对电器设备操作规定正确的有（）。

A、非专职和非值班电气人员，严禁擅自操作电气设备

B、不得用潮湿手指接触电器按钮

C、操作高压电气设备回路时，操作人员必须戴绝缘手套，穿电工绝缘靴，站在绝缘台上，使用绝缘棒或拉杆操作把手进行作业

D、停电时，将工作部分进行放电，封好地线

答案

参考答案：A, B, C, D

改错题

One day I told Mr Wang,our math teacher,was ill.                                                                             61.________

I was worried about him and went to see him after the school.                               62.________

When I enter his room,he struggled up to welcome                                              63.________

me.I let him lay down again.Mr Wang looked pale.                                               64.________

I asked about his trouble.He said he was having                                                    65.________

a bad cold.Then he had a bad cough.After take some                                             66.________

medicine he was getting better.He asked me that we                                              67.________

liked the teacher who took place.When he heard                                                   68.________

everything was all right,I could see he was pleasing.                                             69.________

Finally I asked him don’t to worry about the work                                                70.________

and have a good rest.
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问答题

某同学在“测滑轮组机械效率”的实验中，用图中所示的装置匀速提起重物，并做了如下实验记录：

钩码重G（N）钩码上升高度h（m）测力计拉力

F（N）

测力计移动距离

s（m）

20.10.40.3
（1）如果你对该同学的实验记录进行有关分析，就会发现他的实验结果是违背物理规律的，其表现在于：______．

（2）右图是测力计的放大图．结合左图你会发现导致实验结果违背物理规律原因．其原因是______．

（3）纠正错误后，可计算该滑轮组的机械效率为______．
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