当客户与一方通话时，呼叫第三方，在不中断对方通话的情况下实现与两方通话，这项业务是三方通话业务。
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消防员灭火防护服的主要用途及要求是灭火作业时的身体防护，采用薄型隔热层和透气、耐洗涤性能好的材料。
A. 正确
B. 错误
外电网采集机采样位置在机械室电源箱闸刀上方。
A. 正确
B. 错误
A centrifugal pump produces flow with a resulting discharge head by energy conversionIt is typical for the energy conversion to follow the order of （）.
A. mechanical energy to kinetic energy to potential energy
B. mechanical energy to potential energy to kinetic energy
C. potential energy to mechanical energy to kinetic energy
D. kinetic energy to mechanical energy to potential energy
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