It does no good to shock a dog for not obeying a command they don't already know.
This is such good advice. I see this mistake made all too often. Think of it like being in a foreign prison and you keep getting beaten for not obeying commands given to you in a language you don't even know. Being a human you will try to figure it out but all a dog knows is that its experiencing pain and has no idea why, and two possible reactions are mental breakdown and a fear of training, or trying to protect itself, neither of which is good.