题目

   In front of the church down the street, a manger(马槽) had been set up, with Mary, Joseph, and the barn animals in  47.______ the arrival of baby Jesus. As I walked home, I 48._____ that the story of Joseph and Mary wandering from door to door seeking shelter was much like my own. Leaving Puerto Rico was still a 49._____in my soul and I was struggling with whom I had become in my 15 years in the United States. I’d mourned my losses, 50._____for the first time, I recognized what I’d gained. I was 51.______, and educated and healthy. My life was still before me, full of 52. _有一包白色粉末，可能由、、、和中的一种或几种组成．为了确定它的组成某化学小组学生行了如下探究活动： 提出假设：白色粉末由上述五种物质组成． 步骤1：取少量白色粉末，加足量水溶解后过滤，得到白色沉淀和无色滤液． 步骤2：取少量由步骤1得到的白色沉淀，加入足量稀硝酸后，部分沉淀溶解，并有无色气体产生． 得出结论： (1)原白色粉末中一定没有_____(写化学式)，说明假设不成立． (2)步骤1得到沉淀是______(写化学式)． (3)白色粉末的组成可能是(写化学式)___________．