小明同学在实验室用大理石和稀盐酸反应制取二氧化碳完毕后，对废液中溶质的成分产生了兴趣．请你一同参与探究并回答下列问题：
【提出问题】废液中的溶质是什么物质？
【作出猜想】小明同学认为废液中溶质只有氯化钙．你认为还可能有的溶质是____（填化学式）．
【查阅资料】氯化钙溶液呈中性．
【实验与结论】
（1）小明同学取少量废液于试管中，滴入几滴无色酚酞试液后，酚酞不变色，于是小明同学认为自己的猜想是正确的．
（2）你认为小明同学的实验____（填“能”或“不能”）证明他的猜想，理由是____．
（3）如果要证明你的猜想是正确的，你选择的试剂是____，实验中可以看到的现象是____．
【拓展与应用】
（1）实验证明你的猜想是正确的，要想处理废液只得到氯化钙溶液，你的实验步骤是____．
（2）通过以上探究，如果该废液未经处理直接倒入下水道，可能造成的危害是____（写一条）．
【交流与反思】在分析化学反应后所得物质的成分时，除了考虑生成物外，还需要考虑____．

Once there lived an old man in a town. He always forgot a lot of things. So his wife always had to say to him，“Don’t forget this.”
One day he went on a long way alone. Before he left home，his wife said，“Now you have all these things. You need them on your way. Take care of your things on the way.” He went to the station. He bought a ticket and got on the train with it.
About an hour later，the conductor began to see the tickets. He came to the old man and said，“Will you please show me your ticket?” The old man looked for his ticket in all his pockets but he could not find it. He was very worried.“I can’t find my ticket. I really bought a ticket before I got on the train ”said the old man.
“I think you are right. I believe you bought a ticket. All right，you don’t have to buy another ticket ”said the conductor kindly. But the old man still(仍然) looked worried and said sadly，“You don’t know why I’m worried. If I don’t find my ticket，I can’t remember my station. Where am I going? ”