问题
单项选择题
下列选项中，关于对焊机的安全使用要求，叙述不正确的是( )。
A．对焊机应安置在室内，并应有可靠的接地或接零
B．焊接前，应根据所焊接钢筋截面，调整二次电压，不得焊接超过对焊机规定直径的钢筋
C．断路器的接触点、电极应定期光磨，二次电路全部连接螺栓应定期紧固
D．冷却水温度不得超过30℃
答案
参考答案：D
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下列选项中，关于对焊机的安全使用要求，叙述不正确的是( )。
A．对焊机应安置在室内，并应有可靠的接地或接零
B．焊接前，应根据所焊接钢筋截面，调整二次电压，不得焊接超过对焊机规定直径的钢筋
C．断路器的接触点、电极应定期光磨，二次电路全部连接螺栓应定期紧固
D．冷却水温度不得超过30℃
参考答案：D
When people think of tigers, they think they are strong and dangerous. But now, the big animal is calling for our help. There were once eight kinds of in the world, but three died out during the 20th century. In the last 70 years, the of Siberian tigers (东北虎)has gone from as many as 300 to 22 somewhere, The Siberian tiger has been dying out completely, If the government doesn’t make any efforts, it’s quite that there will be no more Siberian tigers in China in ten to twenty years. In order to double the number of wild tigers in the ten years, the World Wildlife Fund has started a program recently. It save wild tigers and put an end to tiger hunting and killing. China, together with twelve other ,has joined in. Wild animals, such as red deer and wild pigs, are the main of the tigers, The hunting of these animals is the greatest threat(危险)to tigers. So the most important thing is the animals that tigers eat. To protect the wild tigers, we need to call on more people to stop eating and hunting wild animals.
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