用初中所学知识分析化学反应X+Y=Z+R，推论正确的是（　　）

​

为了测定能使带火星的木条复燃的氧气体积分数的最小值，进行了如下的实验：

   a.取5～6只集气瓶，用量筒分别测出它们的容积并标记； 

  b.向集气瓶中分别装入其总容积的10%、20%、30%、40%、50%的水，并用毛玻璃盖住，依次编号为1、2、3、4、5。

   c.在反应容器中加入一定量的MnO₂和H₂O₂使其反应，分别用排水法将上述1～5号瓶中的水排出。

   d.将带火星的木条依次插入1～5号瓶中，观察并记录现象如下表：

阅读材料，回答问题：周平王即位，把都城迁到洛邑，以避开犬戎族的进攻。平王时期，周王室势力已经衰弱，诸侯以强并弱，齐、楚、晋等开始强大起来，政权也由地方诸侯掌握。

   “I sometimes get up at three or four in the morning and I surf the net.”
   “I often check my e-mail forty times a day.”
   “I often spend more than three hours during one time on the net.”
   “I spend more time in chatting rooms than with my 'real-life' friends.”
    Do you know any people like these? They are part of a new addiction(瘾) called Internet addiction. Internet addicts spend at least thirty to forty hours online every week. The use of the Internet can be an addiction like drug(毒品) use. People lose control of the time they spend on the Internet.
   For example, one college student was missing for several days. His friends were worried, and they called the police. The police found the student in the computer lab: he was surfing the net for several days straight.
   Studies show that about 6% to 10% of Internet users become addicted. And people worry about the teens because the Internet is changing the playing field for some of them. They spend more time in cyberspace than in the real world of friends and family. Is 'surfing the net' a hobby or an addiction for you? You may have a problem if you have these symptoms(症状):
    ●You do not go to important family activities or you do not do school work because you like to spend hours on the Internet.
    ●You can't wait for your next online time.
    ●You plan to spend a short time online, but then you spend several hours.
    ●You go out with your friends less and less.