The eighth commandment is to decipher the tone of the person as well as non-verbal cues such as posture and positioning of the arms as this will almost always give away the true demeanor of the person even if they portend otherwise. The ninth commandment dovetails with a lot of the above but it bears repeating, that being to give the person speaking your full attention and make it clear that you are respecting them enough to take in the full conversation. The tenth commandment also dovetails with a lot of the others, and that is to not fidget with anything,...

It is not polite to not give someone your full attention or to try and just your two cents in. This is especially true in the business and academic worlds where manners and politeness matter a lot.