Anchor: Air quality modelers face two key challenges in attempting to translate emission inventories into pollutant concentrations.
Entailed: Air quality models face two key challenges.
Contradiction: Air quality modelers do not face any challenged when attempting to translate emission inventories into pollutant concentrations.
Contradiction: A person is mountain biking.
Contradiction: A boy is holding a blue thing.
Contradiction: The dog is tying knots.
Contradiction: A man is relaxing.