to connect an electrical device to an electrical system or device so that it can be used, by pushing its plug into a socket

Of course the radio isn't working - you haven't plugged it in! 你没有插电源，收音机当然不响了！

I want to plug the kettle into the right-hand socket. 我想把水壶插到右手边的插座上。

Can you show me where the microphone plugs into the tape recorder? 你能给我指一下麦克风接在录音机哪里吗？

The keyboard plugs in at the back of the computer. 键盘接在计算机背后。