Choose the correct missing preposition

1. I plugged
   [on|off|up|down]
   my tablet charger in a socket.
2. I set
   [on|off|up|down] the alarm on my phone.
3. I switched the heating
   [on|off|up|down] because it's too cold here.
4. I turned
   [on|off|up|down] the projector from my laptop. I don't need more sheets.
5. I switched the TV
   [on|off|up|down] because I was tired of watching it.
6. I turned the radio
   [on|off|up|down] because I didn't hear it.