（CH₂CHCl）_n+ $\frac{5n}{2}$ O₂ $\underset{\_}{\underset{\_}{点燃}}$ 2nCO₂+nH₂O+nHCl，其中n是上千或上万的数值；HCl气体极易溶于水，有刺鼻气味，其水溶液即是盐酸；鉴别盐酸的方法是加入AgNO₃溶液，观察是否产生白色沉淀．

①通过点燃的方法可以鉴别聚乙烯和聚氯乙烯．如果塑料袋点燃时有强烈的刺鼻气味，这种塑料袋可能是由____制成的．

②某同学设计了如下图所示实验来探究塑料燃烧的产物．

若A瓶燃烧的是聚氯乙烯塑料，在B瓶中可以看到的现象是____，C、D两瓶中发出反应的化学方程式为____、____；

若A瓶中用的是聚乙烯塑料，则在C瓶中能观察到的现象是____．

公民的合法收入是指（    ）

①自己的工资和奖金   ②承包收入

③炒股赚的钱               ④购买彩票中的奖

读图“俄罗斯地形与矿产分布图”，完成下列各题。

阅读理解，根据短文选择正确的一项

    One day a policeman was walking in the park. He saw a man there. The man was holding a penguin（领着一个企鹅）. The man said to the policeman, “ I found this penguin this morning. What shall I do with it?”“Take it to the zoo,” said the policeman. The next day the policeman saw the man again. He was still holding the penguin. The policeman said, “Why didn't you take the penguin to the zoo?”“I did,” said the man. “I took him to the zoo yesterday. Today I'm taking him to the cinema.

图示为锥形齿轮的传动示意图，大齿轮带动小齿轮转动，大、小齿轮的角速度大小分别为ω₁、ω₂，两齿轮边缘处的线速度大小分别为v₁、v₂，则（   ）