问题
选择题
下列各组气体或溶液用括号内试剂加以鉴别，其中不合理的是（ ）
A．二氧化碳、二氧化硫、一氧化碳（品红试液）
B．氯化钠、硝酸银、碳酸钠（稀盐酸）
C．酒精、醋酸、醋酸钠（石蕊试液）
D．硫酸、硝酸钡、氯化钾（碳酸钠溶液）
答案
答案：A
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下列各组气体或溶液用括号内试剂加以鉴别，其中不合理的是（ ）
A．二氧化碳、二氧化硫、一氧化碳（品红试液）
B．氯化钠、硝酸银、碳酸钠（稀盐酸）
C．酒精、醋酸、醋酸钠（石蕊试液）
D．硫酸、硝酸钡、氯化钾（碳酸钠溶液）
答案：A
Everyone wants to have healthy teeth. When you laugh, you will your mouth and show your teeth. The healthier your teeth are, the happier you feel. Why is that? It's your teeth are important in many ways. Take care of them, and they'll help to take care of you. Strong, teeth help you grow. They also help you speak clearly. You can take care of your teeth by doing like these: Brush your teeth a day, after getting up and before bedtime. And you brush all of your teeth, not just the front ones. Spend some time the teeth along the sides and in the back. Take your time while brushing. Spend at three minutes each time you brush. Be sure your toothbrush is soft. Ask your parents to help you get a new toothbrush three months. Clean between your teeth with dental floss(牙线). It feels strange when you do it at first, but soon you'll get used to it. Brushing your teeth healthy. You also need to care about what you eat and drink. Eat fruits and vegetables and drink water instead of drinks. Do you want to have white and healthy teeth? Please brush your teeth!
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