题目

2011年，“瘦肉精”、“染色馒头”、“塑化剂”等食品安全事件，再次引发国人对食品安全的忧思。对此，政府可以采取的措施是(    ) ①加强市场监督，健全社会信用体系②诚信经营，不出售有毒有害食品③规范市场秩序，完善市场规则④充分发挥国家宏观调控在市场调节中的基础性作用 A． ①③    B．②③     C．①④     D．②④All flights ___________ because of fog. I’m afraid you will have to stay here for another day.A. had been put off B. called offC. have been called off D. have put off