Dear Annie,
   I have never written a letter to a newspaper before, I have just never felt the need to do such a thing. I have always felt I was quite able to do everything by myself. But now I know I was wrong.
   Sometimes you really need help in life, I guess. And that's why I'm writing this letter to you.
I have a happy family. I love my children and they love me . I'm a mother of three children. I know well how to bring up (带大)children, and two of them are already over twenty, so it is nothing new for me.
   But now I have a serious problem: the Internet problem. My little son is just sixteen, and I feel he should do a lot of homework now , but he doesn't seem to be interested in it . He can happily spend six or eight hours at a time on the Internet every day , He chats with people that he has never met before , but speaks little to us .He does lots of useless things on the Internet. And he sees red if you ask him to do his homework.
   I just want him to be a good student . Now he seldom does his lessons at home. I'm afraid he will drop behind in his class soon. His father is a doctor , a very kind man . He never seems to be afraid of his father.
What can I do ?And don't tell to talk to him. We've tried that and it didn’t work. But this is really a big problem in our family. I have tried everything I can think of . I wonder how the Internet is so attractive(有吸引力的).You're my last hope. Please tell me what I can do!
Yours,
Ellen Smith

“84”消毒液在日常生活中使用广泛，具有漂白、杀菌、消毒功效．某化学兴趣小组对一瓶敞口久置的“84”消毒液成分产生兴趣，在老师的指导下，展开探究．

【提出问题】该敞口久置的消毒液中溶质有哪些？

【查阅资料】“84”消毒液主要成分是次氯酸钠（NaClO）和氯化钠，NaClO为有效成分，有腐蚀性并易与空气中CO₂反应（2NaClO+CO₂+H₂O═2HClO+Na₂CO₃）．NaClO溶液、HClO都具有漂泊、杀菌、消毒功效．HClO不稳定，受热或光照会发生分解．

下面的计算正确的是（　　）