单项选择题

An operational amplifier, as used in todays consoles, has a calculated gain of 5This means that when the input changes （）

A.5 volts, the output changes 10 volts
B.10 volts, the output changes 5 volts
C.2 volts, the output changes 10 volts
D.10 volts, the output changes 2 volts

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Electrical failures in motors are caused by the breakdown of insulation, which may be caused by （）

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