plug (something) in/plug (something) into something        
phrasal verb with plug verb [ T ] uk/plʌɡ/ us/plʌɡ/ -gg-
B2 给…接通电源;把(某一电器)与(另一电器)接通
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。