If you want to use the computer,（ ）it（ ）firstA、Turn,on B、Turn,off C、Put,on D、Put,off

If you want to use the computer,（ ）it（ ）firstA、Turn,on B、Turn,off C、Put,on D、Put,off
If you want to use the computer,（ ）it（ ）first
A、Turn,on B、Turn,off C、Put,on D、Put,off

If you want to use the computer,（ ）it（ ）firstA、Turn,on B、Turn,off C、Put,on D、Put,off
A,turn on表示打开

A 意味“把。。。打开” 同样可以用在 （turn on the light)