Question

(04.03r mc)
erosion of certain old buildings may be worsened in big cities by ____, which is related to ____.
acid deposition; air pollutants and particular matter
particulate matter; odorless gas collecting in an area
photochemical smog; reactions between heat and vocs
sulfurous smog; gas burning in very hot weather

Explanation:

• For the first option: Acid deposition (like acid rain) is caused by air pollutants (e.g., sulfur and nitrogen oxides) and particulate matter. Acid deposition can react with building materials (e.g., limestone in old buildings) and worsen erosion.
• For the second option: Particulate matter is solid/liquid particles in air, and "odorless gas collecting in an area" doesn't relate to particulate matter's role in erosion, so this is incorrect.
• For the third option: Photochemical smog is mainly about air quality affecting health and visibility, not directly building erosion, so this is incorrect.
• For the fourth option: Sulfurous smog is from sulfur - containing fuel burning, but "gas burning in very hot weather" is an incorrect description of its cause, and it's not the main factor for building erosion compared to acid deposition.

Answer:

A. acid deposition; air pollutants and particular matter