A casualty report of an intentional grounding of a ship is required under what condition?()
A. Under any condition
B. If the grounding lasts over 24 hours
C. If it creates a hazard to the environment
D. At the owner's discretio
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漏电保护器,应每月检查一次,即操作(),检查其是否能正常断开电源。
密封泄漏、振动、流量不足、轴承温度高、电机过载是离心泵的常见故障。
A. 正确
B. 错误
()是电力机车、电动车辆从接触网接触导线上受取电流的一种受流装置。