vacuum tube voltmeter circuit

例句：

1. 1. The vacuum tube was the first electronic device invented by Edison.
   真空管是爱迪生发明的第一种电子装置。
2. 2. The vacuum tube is used in many electronic devices.
   真空管被用于许多电子设备中。
3. 3. The vacuum tube was a revolutionary invention that changed the way we communicate.
   真空管是一种革命性的发明，改变了我们交流的方式。
4. 1. The voltage meter showed the power supply was working properly.
   电压表显示电源工作正常。
5. 2. The engineer used the voltmeter to measure the voltage across the circuit.
   工程师使用电压表测量电路两端的电压。
6. 3.Voltmeters are used to measure the voltage of electrical circuits.
   电压表用于测量电气电路的电压。