问题
问答题 简答题
为什么采用拉路方法查找直流接地有时找不到接地点？
答案
参考答案：
采用拉路方法找不到接地点的可能的原因如下。
⑴直流接地发生在充电设备、蓄电池本身和直流母线，这时用拉路方法是找不到接地的。
⑵直流采用环路供电，这时如不先断开环路也是找不到接地点的。
⑶出现直流串电（寄生回路）、同极两点接地、直流系统绝缘不良等情况时，拉路查找也往往不能奏效。
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为什么采用拉路方法查找直流接地有时找不到接地点？
参考答案：
采用拉路方法找不到接地点的可能的原因如下。
⑴直流接地发生在充电设备、蓄电池本身和直流母线，这时用拉路方法是找不到接地的。
⑵直流采用环路供电，这时如不先断开环路也是找不到接地点的。
⑶出现直流串电（寄生回路）、同极两点接地、直流系统绝缘不良等情况时，拉路查找也往往不能奏效。
When you go shopping, you may not be aware of all the thought and planning which has been put into the design of products. The only aim of all this thought and planning is to make us __1__ as much of our money as possible. Packaging is a very important area in product __2__. Some companies even hire psychologists to make __3__ or do experiments on packaging. In one __4__ experiment, some psychologists wanted to find the best __5__ for a new soap powder. They decided to test the colours blue and yellow. Three different boxes were designed. Some boxes were blue, some were yellow and some were a __6__ of blue and yellow. The same powder was out in all three boxes, a group of women was given the new soap powder in order to __7__ it. The results were very interesting. The powder in the yellow packet was said to be much too __8__. However, the women thought that the powder in the blue box was much too weak. They felt the powder in the __9__ box to be the best powder. So we had better remember never to judge goods by their packaging! We must not allow ourselves to be __10__ into spending more money than we can afford.
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