题目

I always remember one Christmas when we ______ outside of town. My older brother had a job in a different city ______ he always made it home to celebrate the holidays. During the few days before Christmas Day, we _____ a violent snowstorm with powerful winds. It was so ______ that the country road was almost impassable.The day before Christmas was more ______ than I had ever imagined. My older brother was stuck at a stranger’s home where he had been ______ to stay overnight because of the storm. The person was _______enough to let him stay until morning. But, the ______ was that he couldn’在做完盐的性质实验后，某实验小组欲对废液成分进行研究．根据实验所用药品，他们初步分析该废液中可能含有HCl、NaCl、Na2SO4、Na2CO3、KNO3中的几种．为确定废液成分，他们设计了如下过程进行实验． 请仔细分析实验过程，回答下列问题：（1）步骤③、⑥的操作方法是；（2）白色固体A的化学式为；（3）步骤⑤中发生反应的化学方程式为；（4）废液中除了水以外，一定含有的物质是 ， 可能含有的物质是 ．（5）溶液D中一定含有的溶质是 ．