25T型客车的蓄电池组应有短路保护,各极对箱体间的绝缘电阻应不小于()。
A. 20M欧
B. 10M欧
C. 15M欧
D. 5M欧
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Accidental grounds in a shipboard electrical system must be repaired as soon as possible as they will ()
A. result in immediate power outages
B. damage circuit breakers
C. appear on the ground detection system
D. damage insulation and may cause outage
风湿性疾病活检组织病理改变对诊断有决定性意义,并有指导治疗的作用。如唇腺活检有助于()
A. 诊断干燥综合征
B. 诊断SLE
C. 诊断类风湿关节炎
D. 诊断皮肌炎
E. 辅助诊断狼疮肾炎
离心泵在零流量下运转时间不能超过()min,否则易过热而损坏机件。
A. 1
B. 3
C. 5
D. 10