① 求冰块的体积V_冰。

② 若冰块吸热后，有3×10^-3米³的冰熔化成水，求水的质量m_水。

人类可以生产产品、创造财富，是城市生态系统中的生产者。（判断对错）

 据报道，“中东呼吸综合征”病毒与“非典”病毒类似，加强自身防护是抵御病毒的重要方法．过氧乙酸（化学式为C₂H₄O₃）是常用的一种消毒剂．请计算（直接写出答案）：

（1）过氧乙酸（化学式为C₂H₄O₃）的相对分子质量；

（2）过氧乙酸中氢、氧两种元素的质量比．

A Policeman and a Thief  
One day a policeman was taking a thief to the city . On the way , they saw a shop . The thief said . “ Let me go into the shop to buy some bread . We can eat it in the train . ”
The policeman agreed . The thief went into the shop and ran out of the back door . When the policeman knew that , he began to look for the thief everywhere . At last the policeman caught(抓获) thief again . They went on to the city . On the way they came to the same shop . The thief wanted to buy some bread again . “Oh , no . ” said the policeman , “You did that before , and you ran away . This time I^’ll go into the shop and buy bread . You must wait here for me . ”