17. Our present understanding of the Sun's luminosity holds that it should have progressively increased, not decreased, over the course of Earth's history.
当前我们对太阳光度的认知是：在地球的历史进程上，太阳光度应该是逐渐增加而不是减少的。
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18. Evidence from other studies suggests that exclusion of fire results in markedly decreased plant-species richness, often with an increase in tree density.
来自其他研究的证据表明，没有火灾会导致植物物种丰富性显著减少，通常还会伴随着树木密度的增加。
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19. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.
在《清洁空气法案》强制要求美国使用无铅气体的二十年里，铅在世界范围内的累积量显著下降。
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20. In the past, every ten-percentage-point increase in cigarette prices in the country of Coponia has decreased per capita sales of cigarettes by four percent.
过去，科普尼亚的香烟价格每上涨10个百分点，人均香烟销量就会下降4%。
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21. But since 1980, the amount of water consumed per person has actually decreased, thanks to a range of new technologies that help to conserve water in homes and industry.
但自1980年以来，在一系列帮助家庭和工业节水的新技术应用之后，人均用水量实际上有所下降。
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22. Among student subjects who discussed meat ethics, meal purchases containing meat decreased from 52 to 45 percent—and this effect held steady for the study's duration of several weeks.
23. In a study published in the journal Ambio, scientists found that lead levels in soil in the North-eastern United States had decreased markedly since the introduction of unleaded gasoline.
24. Smith counters that if you factor in the hidden cost of government corn subsidies, environment degradation, and decreased human health and animal welfare, grass-fed is the more cost-effective model.
