Not necessarily such as Cu and Fe and concentrated nitric acid composition of primary batteries due to passivation of Fe and concentrated nitric acid, so Fe do positive Cu do negative
So specific analysis can not rote memorization to remember the principle of the most important!
The thickness of the passivation film is limited, and the resistance of the passivation film is also limited, not absolutely non-conductive.
Aluminum does not conduct electricity after passivation. The reason is that after the passivation of aluminum, a dense oxide is formed on its surface, and the oxide is not conductive.
Aluminum can conduct electricity because aluminum is a metal, and there are freely moving electrons inside the metal crystal, and freely moving electrons can be charged from one end to the other, and they can conduct electricity.