题目

Bushwick is a tough place to grow up. This part of Brooklyn, in New York City, has a lot of crimes. More than half of its 100,000 residents rely on aid from the government. Only 50% of students at Bushwick High School graduate in four years. Some people might say, “We should help these poor kids who have so many challenges.” But Malaak Compton-Rock looks at the teens in Bushwick and says, “Go to help kids who have even bigger challenges than you do.” She believes that once young people see the power they have to make things better, they can handle their own problems more easily. So her（2008?佛山）以下对实验现象的分析合理的是（ ）①向某无色溶液中滴入紫色石蕊试液，溶液变蓝色，证明该溶液呈碱性②向某无色溶液中滴入氯化钡溶液，产生白色沉淀，证明该溶液是硫酸溶液③某白色固体与熟石灰混合后加热，产生可使湿润的pH试纸变蓝色的气体，证明该固体是铵盐④把燃着的木条伸入某无色气体的集气瓶中，火焰熄灭，证明该气体是二氧化碳．A．①③B．③④C．①④D．①②③④