题目

You are what you eat     Keeping better eating habits can help you have less illness. A healthy eating plan means choosing the right food to eat and cooking food in a healthy way. ___________ Do you often change your toothbrush? Maybe you think it is unnecessary. A study shows old toothbrushes bring disease(病菌). You should often change your toothbrush. Exercise     Swimming, cycling, jogging, skating, dancing, walking and some other activities can help you stay healthy. You should exercise at least three times a week and for twenty minutes or more each time. Do it! Plan out yo（2006?山西）某工厂废液中含有AgNO3和Cu（NO3）2，为了有效利用和回收有用物质，某同学在废液样品中加入了一定量的铁粉，充分反应后过滤，在滤渣中滴加稀盐酸，有无色可燃性气体生成，则其中滤渣的成分是（此空答不全不给分），滤液中含有的溶质是．写出其中的一个化学反应方程式．