Need help about rusting

Example 1:
Painting of window frames: The painting can keep the window frames away from air (oxygen and water).

Example 2:
Tin-plating of food can: The tin-plating layer can keep the iron can away from air (oxygen and water).

Example 3:
Sacrificial protection: Put a zinc block in contact with underwater iron pipe. Zinc is more reactive than iron, and is thus corroded first to prevent the rusting of iron.

遠離水份，遠離空氣，遠離火種，生鏽係氧化物係金屬接觸空氣氧份產生。