腐食

1. Origins, structure, and basic meaning

• Structure: 腐食 is read as ふしょく and functions as a noun or with する for corrosion that damages a material's surface under environmental exposure.
• Basic usage: The material is the subject in 金属の柵が腐食する, while the process prevented is the object in 腐食を防ぐ.

2. Common pitfalls and similar expressions

• Subject and prevented process
  • が marks the metal fence that corrodes, whereas を marks corrosion as the phenomenon a coating is meant to prevent.
• Cause and countermeasure
  • Sea air is presented as the cause and paint as the protective measure, so their roles in the two expressions differ.