GRE Reading Comprehension: PPO-GRE阅读PPO - 1809BTCC5MRD513BS

According to ancient records, the first sales tax that the government of Selea imposed was a tax of two centime coins on every jar of cooking oil sold in Selea. Tax records show that despite a stable population, revenues from the oil tax declined steeply over the first two years that the tax was in effect. Therefore, a significant proportion of Seleans must have failed to pay taxes on the cooking oil they purchased.