题目

阅读理解 On her first morning in America, last summer, my daughter wentout to explore her new neighborhood alone. Of course we were worried; we had just moved from Berlin, andshe was just 8. But when she came home, we realized we had no reason to worry. Shetold us with pride how she had discovered the little park around the corner, andhad made friends with a few local dog owners. When this story comes up in conversations with American friends,we are usually met with polite disbelief. A study by the University of California has found that Americankids spend 90 percent of their free time at 稀盐酸中混有少量硫酸，为除去硫酸，可加入的试剂是（ ）A．适量铁粉B．适量硝酸钡溶液C．适量氢氧化钡溶液D．适量氯化钡溶液