题目

       Olympic champion Carl Lewis begins the 34th annual Hershey's (好时巧克力公司)Track and Field Games. Nine-time gold medalist Carl Lewis has teamed up with Hershey’s for the 34th annual Hershey's Track and Field Games. The goal of the Games, which take place in 4,000 communities throughout North America, is to promote physical fitness and sportsmanship in kids aged 9 to 14.        Why is a chocolate company encouraging kids to get fit? “Everyone should get involved in helping kids to get active.” Lewis says. “We should all be responsible. It's great that当空气受SO2严重污染时，可通过飞机喷洒X粉末，使空气中的SO2含量明显降低，该过程发生的反应是：2X +2SO2+O2=2CaSO4 +2CO2。则X的化学式是   A．CaO          B．CaCO3         C．Ca(OH)2        D．Na2CO3