This formula is satisfiable because if we set to b to true and a to false, then the whole formula is true. All other assignments make the formula false, but it doesn't change that the formula is satisfiable as long as there is at least one assignment makes the formula true.
（五）提供信息搜索服务的，应当采取监测发现、防范、阻断、处置违法信息传播、推广的措施；提供付费信息搜索服务的，应当依法核验客户资质，明确付费搜索信息页面比例上限，并对付费搜索信息加注显著标识；
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Photograph: Julian Chokkattu。同城约会对此有专业解读
Petrochemicals – of which plastics are the dominant output – now account for roughly 75% of net global oil-demand growth, and are projected to become the largest driver of future oil demand. Plastic production has already doubled in the past two decades. Major oil companies are responding accordingly. Recent consolidation – including a $60bn merger creating one of the world’s largest plastics producers – reflects a deliberate pivot toward petrochemical assets as a long-term demand anchor.，详情可参考safew官方下载